Grep игнорировать ошибки - Не ошибается лишь тот, кто ничего не делает!

I’m grepping through a large pile of code managed by git, and whenever I do a grep, I see piles and piles of messages of the form:

> grep pattern * -R -n
whatever/.git/svn: No such file or directory

Is there any way I can make those lines go away?

asked Jun 21, 2011 at 13:48

alexgolecalexgolec

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You can use the -s or --no-messages flag to suppress errors.

-s, —no-messages suppress error messages

grep pattern * -s -R -n

answered Jun 21, 2011 at 13:51

If you are grepping through a git repository, I’d recommend you use git grep. You don’t need to pass in -R or the path.

git grep pattern

That will show all matches from your current directory down.

answered Jun 21, 2011 at 13:53

Steve PrenticeSteve Prentice

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Errors like that are usually sent to the «standard error» stream, which you can pipe to a file or just make disappear on most commands:

grep pattern * -R -n 2>/dev/null

answered Jun 21, 2011 at 13:51

lunixbochslunixbochs

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I have seen that happening several times, with broken links (symlinks that point to files that do not exist), grep tries to search on the target file, which does not exist (hence the correct and accurate error message).

I normally don’t bother while doing sysadmin tasks over the console, but from within scripts I do look for text files with «find», and then grep each one:

find /etc -type f -exec grep -nHi -e "widehat" {} ;

Instead of:

grep -nRHi -e "widehat" /etc

j0k

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answered Aug 9, 2012 at 14:13

I usually don’t let grep do the recursion itself. There are usually a few directories you want to skip (.git, .svn…)

You can do clever aliases with stances like that one:

find . ( -name .svn -o -name .git ) -prune -o -type f -exec grep -Hn pattern {} ;

It may seem overkill at first glance, but when you need to filter out some patterns it is quite handy.

answered Jun 21, 2011 at 13:57

cadriancadrian

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Have you tried the -0 option in xargs? Something like this:

ls -r1 | xargs -0 grep 'some text'

Kjuly

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answered Jan 20, 2012 at 6:38

cokedudecokedude

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Use -I in grep.

Example: grep SEARCH_ME -Irs ~/logs.

answered Oct 8, 2013 at 23:47

I redirect stderr to stdout and then use grep’s invert-match (-v) to exclude the warning/error string that I want to hide:

grep -r <pattern> * 2>&1 | grep -v "No such file or directory"

answered Apr 16, 2020 at 2:35

I was getting lots of these errors running «M-x rgrep» from Emacs on Windows with /Git/usr/bin in my PATH. Apparently in that case, M-x rgrep uses «NUL» (the Windows null device) rather than «/dev/null». I fixed the issue by adding this to .emacs:

;; Prevent issues with the Windows null device (NUL)
;; when using cygwin find with rgrep.
(defadvice grep-compute-defaults (around grep-compute-defaults-advice-null-device)
  "Use cygwin's /dev/null as the null-device."
  (let ((null-device "/dev/null"))
    ad-do-it))
(ad-activate 'grep-compute-defaults)

answered Jul 21, 2020 at 23:47

beaslerabeaslera

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One easy way to make grep return zero status all the time is to use || true

 → echo "Hello" | grep "This won't be found" || true

 → echo $?
   0

As you can see the output value here is 0 (Success)

answered Mar 3, 2021 at 23:09

Many answers, but none works, sigh

 grep "nick-banner" *.html -R -n

It does not work:

grep: *.html: No such file or directory

answered Mar 2 at 18:46

TeemuTeemu

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Problem:

This drove me bananas. I tried everything under the (Google) Sun and nothing worked with this grep which just puked repeated errors about «sysctl: reading key …» before finally printing the match:

sudo sysctl -a | grep vm.min_free_kbytes

Solution:

Nothing worked UNTIL I had an epiphany: What if I filtered in the front rather than at the back?… Yup: that worked:

sysctl -a --ignore 2>/dev/null | grep vm.min_free_kbytes

Conclusion:

Obviously not every command will have the --ignore switch, but it’s an example of how I got around the problem filtering BEFORE my grep. Don’t get so blinkered you chase your tail pursuing something that won’t work

answered Mar 31 at 19:04

F1LinuxF1Linux

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Источник

I am trying to find the installation directory of a particular package. I have a certain keyword using which I am trying to find a particular file.

During grep, I only want to include cpp or h file type. I do not want the grep to show warnings like Permission Denied or Could not find the Directory.
I just want it to display matched files, nothing else. Please suggest how can I do this?

At present I am using

grep "My term" -ir --exclude-dir=".svn" --include=*.{cpp,h} ./

Kees Cook

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asked Mar 26, 2011 at 14:22

Those warnings are directed to the stderr stream, as opposed to the standard out file descriptor. You can silence the stderr output by adding 2>/dev/null to the end of your command.

answered Mar 26, 2011 at 14:26

James HenstridgeJames Henstridge

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More directly than filtering the warnings you can disable them by adding -s:

grep "My term" -sir --exclude-dir=".svn" --include=*.{cpp,h} ./

There are some compatibility issues with this option. However, this shouldn’t be a problem for personal use.

-s, —no-messages:
Suppress error messages about nonexistent or unreadable files. Portability note: unlike GNU grep, 7th Edition Unix grep did
not conform to POSIX, because it
lacked -q and its -s option behaved like GNU grep’s -q option. USG-style grep also lacked -q but its -s option behaved like
GNU grep. Portable shell scripts
should avoid both -q and -s and should redirect standard and error output to /dev/null instead. (-s is specified by POSIX.)

answered May 25, 2013 at 14:15

I used to get a ton of annoying messages like this:

grep: commands: Is a directory
grep: events: Is a directory
grep: views: Is a directory

The reason is that the --directories flag is defaulted to read. I changed it to recurse; if you don’t want it to automatically do a recursive search you can use skip instead.

The easiest way to handle this all the time is to set it in an environment variable. In ~/.bash_profile or ~/.bashrc depending on your distro:

export GREP_OPTIONS='--directories=recurse'

Now it automatically suppresses those messages any time I use grep.

Another option is the --no-messages flag, shorthand -s. This will also get rid of the Is a directory messages, but it also suppresses other messages which might be more useful. For example, if you’re doing a nested search in */*/* and no such file of that pattern exists, it won’t tell you that.

answered Oct 2, 2015 at 21:28

Alternative approach instead of doing grep recursively with -ir would be to let find command (which is recursive by default) handle the permissions with -readable flag and path’s to exclude with -not -path "*.svn*" flags, and then pass the file to grep. Excluding directories is done via -type f for finding only regular files.

$ find . -not -path "*.svn*" -type f -name "*.cpp" -or -name "*.h"  -readable -exec grep "my terms" "{}" ;

answered Feb 5, 2017 at 18:10

When doing recursive searches in specific files, you are much better off using ack-grep. The syntax here would be:

ack-grep -i "My term" --cpp --h

To remove the permission error messages, you may want to run the same command with sudo:

ack-grep -i "My term" --cpp --h

But eventually, if you want to search installed packages, look at those various options: https://www.google.com/search?q=ubuntu%20search%20inside%20installed%20packages

wjandrea

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answered Jul 25, 2014 at 15:12

dargauddargaud

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Источник

Short answer

Write

ps -ef | grep bar | { grep -v grep || test $? = 1; }

if you are using set -e.

If you use bash’s pipefail option (set -o pipefail), remember to apply the exception handling (||test) to every grep in the pipeline:

ps -ef | { grep bar || test $? = 1; } | { grep -v grep || test $? = 1; }

In shell scripts I suggest you to use the ”catch-1-grep“ (c1grep) utility function:

c1grep() { grep "$@" || test $? = 1; }

Explained

grep‘s exit status is either 0, 1 or 2: [1]

0 means a line is selected
1 means no lines were selected
2 means an error occurred

grep can also return other codes if it’s interrupted by a signal (e.g. 130 for SIGINT).

Since we only want to ignore exit status 1, we use test to suppress that specific exit status.

If grep returns 0, test is not run.
If grep returns 1, test is run and returns 0.
If grep returns any other value, test is run and returns 1.

In the last case, the script will exit immediately due to set -e or set -o pipefail. However, if you don’t care about grep errors at all, you can of course write

ps -ef | grep bar | { grep -v grep || true; }

as suggested by Sean.

[additional] usage in shell scripts

In shell scripts, if you are using grep a lot, I suggest you to define an utility function:

# "catch exit status 1" grep wrapper
c1grep() { grep "$@" || test $? = 1; }

This way your pipe will get short & simple again, without losing the features of set -e and set -o pipefail:

ps -ef | c1grep bar | c1grep -v grep

FYI:

I called it c1grep to emphasize it’s simply catching exit status 1, nothing else.
I could have called the function grep instead (grep() { env grep "$@" ...; }), but I prefer a less confusing and more explicit name, c1grep.

[additional] `ps` + `grep`

So if you want to know how to avoid grep -v grep or even the | grep part of ps|grep at all, take a look at some of the other answers; but this is somewhat off-topic imho.

[1] grep manpage

Источник

GREP(1)

User Commands

GREP(1)

NAME

grep — print lines that match patterns

SYNOPSIS

grep [OPTION…] PATTERNS [FILE…]

grep [OPTION…] -e PATTERNS … [FILE…]

grep [OPTION…] -f PATTERN_FILE …
[FILE…]

DESCRIPTION

grep searches for PATTERNS in each FILE.
PATTERNS is one or more patterns separated by newline characters, and
grep prints each line that matches a pattern. Typically
PATTERNS should be quoted when grep is used in a shell
command.

A FILE of “—” stands for standard
input. If no FILE is given, recursive searches examine the working
directory, and nonrecursive searches read standard input.

OPTIONS

Generic Program Information

—help: Output a usage message and exit.
-V, —version: Output the version number of grep and exit.

Pattern Syntax

-E,
—extended-regexp: Interpret PATTERNS as extended regular expressions (EREs, see
below).
-F,
—fixed-strings: Interpret PATTERNS as fixed strings, not regular expressions.
-G,
—basic-regexp: Interpret PATTERNS as basic regular expressions (BREs, see below).
This is the default.
-P,
—perl-regexp: Interpret PATTERNS as Perl-compatible regular expressions (PCREs).
This option is experimental when combined with the -z
(—null-data) option, and grep -P may warn of unimplemented
features.

Matching Control

-e PATTERNS, —regexp=PATTERNS: Use PATTERNS as the patterns. If this option is used multiple times
or is combined with the -f (—file) option, search for all
patterns given. This option can be used to protect a pattern beginning
with “-”.
-f FILE, —file=FILE: Obtain patterns from FILE, one per line. If this option is used
multiple times or is combined with the -e (—regexp) option,
search for all patterns given. The empty file contains zero patterns, and
therefore matches nothing. If FILE is — , read patterns from
standard input.
-i,
—ignore-case: Ignore case distinctions in patterns and input data, so that characters
that differ only in case match each other.
—no-ignore-case: Do not ignore case distinctions in patterns and input data. This is the
default. This option is useful for passing to shell scripts that already
use -i, to cancel its effects because the two options override each
other.
-v,
—invert-match: Invert the sense of matching, to select non-matching lines.
-w,
—word-regexp: Select only those lines containing matches that form whole words. The test
is that the matching substring must either be at the beginning of the
line, or preceded by a non-word constituent character. Similarly, it must
be either at the end of the line or followed by a non-word constituent
character. Word-constituent characters are letters, digits, and the
underscore. This option has no effect if -x is also specified.
-x,
—line-regexp: Select only those matches that exactly match the whole line. For a regular
expression pattern, this is like parenthesizing the pattern and then
surrounding it with ^ and $.

General Output Control

-c, —count: Suppress normal output; instead print a count of matching lines for each
input file. With the -v, —invert-match option (see above),
count non-matching lines.
—color[=WHEN],
—colour[=WHEN]: Surround the matched (non-empty) strings, matching lines, context lines,
file names, line numbers, byte offsets, and separators (for fields and
groups of context lines) with escape sequences to display them in color on
the terminal. The colors are defined by the environment variable
GREP_COLORS. WHEN is never, always, or
auto.
-L,
—files-without-match: Suppress normal output; instead print the name of each input file from
which no output would normally have been printed.
-l,
—files-with-matches: Suppress normal output; instead print the name of each input file from
which output would normally have been printed. Scanning each input file
stops upon first match.
-m NUM, —max-count=NUM: Stop reading a file after NUM matching lines. If NUM is
zero, grep stops right away without reading input. A NUM of
-1 is treated as infinity and grep does not stop; this is the
default. If the input is standard input from a regular file, and
NUM matching lines are output, grep ensures that the
standard input is positioned to just after the last matching line before
exiting, regardless of the presence of trailing context lines. This
enables a calling process to resume a search. When grep stops after
NUM matching lines, it outputs any trailing context lines. When the
-c or —count option is also used, grep does not
output a count greater than NUM. When the -v or
—invert-match option is also used, grep stops after
outputting NUM non-matching lines.
-o,
—only-matching: Print only the matched (non-empty) parts of a matching line, with each
such part on a separate output line.
-q, —quiet,
—silent: Quiet; do not write anything to standard output. Exit immediately with
zero status if any match is found, even if an error was detected. Also see
the -s or —no-messages option.
-s,
—no-messages: Suppress error messages about nonexistent or unreadable files.

Output Line Prefix Control

-b,
—byte-offset: Print the 0-based byte offset within the input file before each line of
output. If -o (—only-matching) is specified, print the
offset of the matching part itself.
-H,
—with-filename: Print the file name for each match. This is the default when there is more
than one file to search. This is a GNU extension.
-h,
—no-filename: Suppress the prefixing of file names on output. This is the default when
there is only one file (or only standard input) to search.
—label=LABEL: Display input actually coming from standard input as input coming from
file LABEL. This can be useful for commands that transform a file’s
contents before searching, e.g., gzip -cd foo.gz | grep —label=foo -H
‘some pattern’. See also the -H option.
-n,
—line-number: Prefix each line of output with the 1-based line number within its input
file.
-T,
—initial-tab: Make sure that the first character of actual line content lies on a tab
stop, so that the alignment of tabs looks normal. This is useful with
options that prefix their output to the actual content:
-H,-n, and -b. In order to improve the probability
that lines from a single file will all start at the same column, this also
causes the line number and byte offset (if present) to be printed in a
minimum size field width.
-Z, —null: Output a zero byte (the ASCII NUL character) instead of the
character that normally follows a file name. For example, grep -lZ
outputs a zero byte after each file name instead of the usual newline.
This option makes the output unambiguous, even in the presence of file
names containing unusual characters like newlines. This option can be used
with commands like find -print0, perl -0, sort -z,
and xargs -0 to process arbitrary file names, even those that
contain newline characters.

Context Line Control

-A NUM, —after-context=NUM: Print NUM lines of trailing context after matching lines. Places a
line containing a group separator (—) between contiguous groups of
matches. With the -o or —only-matching option, this has no
effect and a warning is given.
-B NUM, —before-context=NUM: Print NUM lines of leading context before matching lines. Places a
line containing a group separator (—) between contiguous groups of
matches. With the -o or —only-matching option, this has no
effect and a warning is given.
-C NUM,
—NUM, —context=NUM: Print NUM lines of output context. Places a line containing a group
separator (—) between contiguous groups of matches. With the
-o or —only-matching option, this has no effect and a
warning is given.
—group-separator=SEP: When -A, -B, or -C are in use, print SEP
instead of — between groups of lines.
—no-group-separator: When -A, -B, or -C are in use, do not print a
separator between groups of lines.

File and Directory Selection

-a, —text: Process a binary file as if it were text; this is equivalent to the
—binary-files=text option.
—binary-files=TYPE: If a file’s data or metadata indicate that the file contains binary data,
assume that the file is of type TYPE. Non-text bytes indicate
binary data; these are either output bytes that are improperly encoded for
the current locale, or null input bytes when the -z option is not
given.

By default, TYPE is binary, and grep suppresses
output after null input binary data is discovered, and suppresses output
lines that contain improperly encoded data. When some output is
suppressed, grep follows any output with a message to standard
error saying that a binary file matches.

If TYPE is without-match, when grep discovers null
input binary data it assumes that the rest of the file does not match;
this is equivalent to the -I option.

If TYPE is text, grep processes a binary file as if
it were text; this is equivalent to the -a option.

When type is binary, grep may treat non-text bytes as
line terminators even without the -z option. This means choosing
binary versus text can affect whether a pattern matches a
file. For example, when type is binary the pattern q$
might match q immediately followed by a null byte, even though
this is not matched when type is text. Conversely, when
type is binary the pattern . (period) might not match
a null byte.

Warning: The -a option might output binary garbage, which
can have nasty side effects if the output is a terminal and if the
terminal driver interprets some of it as commands. On the other hand, when
reading files whose text encodings are unknown, it can be helpful to use
-a or to set LC_ALL=’C’ in the environment, in order to find
more matches even if the matches are unsafe for direct display.

-D ACTION, —devices=ACTION: If an input file is a device, FIFO or socket, use ACTION to process
it. By default, ACTION is read, which means that devices are
read just as if they were ordinary files. If ACTION is skip,
devices are silently skipped.
-d ACTION, —directories=ACTION: If an input file is a directory, use ACTION to process it. By
default, ACTION is read, i.e., read directories just as if
they were ordinary files. If ACTION is skip, silently skip
directories. If ACTION is recurse, read all files under each
directory, recursively, following symbolic links only if they are on the
command line. This is equivalent to the -r option.
—exclude=GLOB: Skip any command-line file with a name suffix that matches the pattern
GLOB, using wildcard matching; a name suffix is either the whole
name, or a trailing part that starts with a non-slash character
immediately after a slash (/) in the name. When searching
recursively, skip any subfile whose base name matches GLOB; the
base name is the part after the last slash. A pattern can use *,
?, and […] as wildcards, and to quote a
wildcard or backslash character literally.
—exclude-from=FILE: Skip files whose base name matches any of the file-name globs read from
FILE (using wildcard matching as described under
—exclude).
—exclude-dir=GLOB: Skip any command-line directory with a name suffix that matches the
pattern GLOB. When searching recursively, skip any subdirectory
whose base name matches GLOB. Ignore any redundant trailing slashes
in GLOB.
-I: Process a binary file as if it did not contain matching data; this is
equivalent to the —binary-files=without-match option.
—include=GLOB: Search only files whose base name matches GLOB (using wildcard
matching as described under —exclude). If contradictory
—include and —exclude options are given, the last matching
one wins. If no —include or —exclude options match, a file
is included unless the first such option is —include.
-r,
—recursive: Read all files under each directory, recursively, following symbolic links
only if they are on the command line. Note that if no file operand is
given, grep searches the working directory. This is equivalent to
the -d recurse option.
-R,
—dereference-recursive: Read all files under each directory, recursively. Follow all symbolic
links, unlike -r.

Other Options

—line-buffered: Use line buffering on output. This can cause a performance penalty.
-U, —binary: Treat the file(s) as binary. By default, under MS-DOS and MS-Windows,
grep guesses whether a file is text or binary as described for the
—binary-files option. If grep decides the file is a text
file, it strips the CR characters from the original file contents (to make
regular expressions with ^ and $ work correctly). Specifying
-U overrules this guesswork, causing all files to be read and
passed to the matching mechanism verbatim; if the file is a text file with
CR/LF pairs at the end of each line, this will cause some regular
expressions to fail. This option has no effect on platforms other than
MS-DOS and MS-Windows.
-z,
—null-data: Treat input and output data as sequences of lines, each terminated by a
zero byte (the ASCII NUL character) instead of a newline. Like the
-Z or —null option, this option can be used with commands
like sort -z to process arbitrary file names.

REGULAR EXPRESSIONS

A regular expression is a pattern that describes a set of strings.
Regular expressions are constructed analogously to arithmetic expressions,
by using various operators to combine smaller expressions.

grep understands three different versions of regular
expression syntax: “basic” (BRE), “extended”
(ERE) and “perl” (PCRE). In GNU grep, basic and
extended regular expressions are merely different notations for the same
pattern-matching functionality. In other implementations, basic regular
expressions are ordinarily less powerful than extended, though occasionally
it is the other way around. The following description applies to extended
regular expressions; differences for basic regular expressions are
summarized afterwards. Perl-compatible regular expressions have different
functionality, and are documented in pcre2syntax(3) and
pcre2pattern(3), but work only if PCRE support is enabled.

The fundamental building blocks are the regular expressions that
match a single character. Most characters, including all letters and digits,
are regular expressions that match themselves. Any meta-character with
special meaning may be quoted by preceding it with a backslash.

The period . matches any single character. It is
unspecified whether it matches an encoding error.

Character Classes and Bracket Expressions

A bracket expression is a list of characters enclosed by
[ and ]. It matches any single character in that list. If the
first character of the list is the caret ^ then it matches any
character not in the list; it is unspecified whether it matches an
encoding error. For example, the regular expression [0123456789]
matches any single digit.

Within a bracket expression, a range expression consists of
two characters separated by a hyphen. It matches any single character that
sorts between the two characters, inclusive, using the locale’s collating
sequence and character set. For example, in the default C locale,
[a-d] is equivalent to [abcd]. Many locales sort characters in
dictionary order, and in these locales [a-d] is typically not
equivalent to [abcd]; it might be equivalent to [aBbCcDd], for
example. To obtain the traditional interpretation of bracket expressions,
you can use the C locale by setting the LC_ALL environment variable
to the value C.

Finally, certain named classes of characters are predefined within
bracket expressions, as follows. Their names are self explanatory, and they
are [:alnum:], [:alpha:], [:blank:], [:cntrl:],
[:digit:], [:graph:], [:lower:], [:print:],
[:punct:], [:space:], [:upper:], and [:xdigit:].
For example, [[:alnum:]] means the character class of numbers and
letters in the current locale. In the C locale and ASCII character set
encoding, this is the same as [0-9A-Za-z]. (Note that the brackets in
these class names are part of the symbolic names, and must be included in
addition to the brackets delimiting the bracket expression.) Most
meta-characters lose their special meaning inside bracket expressions. To
include a literal ] place it first in the list. Similarly, to include
a literal ^ place it anywhere but first. Finally, to include a
literal — place it last.

Anchoring

The caret ^ and the dollar sign $ are
meta-characters that respectively match the empty string at the beginning
and end of a line.

The Backslash Character and Special Expressions

The symbols < and > respectively match the
empty string at the beginning and end of a word. The symbol b
matches the empty string at the edge of a word, and B matches the
empty string provided it’s not at the edge of a word. The symbol
w is a synonym for [_[:alnum:]] and W is a synonym
for [^_[:alnum:]].

Repetition

A regular expression may be followed by one of several repetition
operators:

?: The preceding item is optional and matched at most once.
*: The preceding item will be matched zero or more times.
+: The preceding item will be matched one or more times.
{n}: The preceding item is matched exactly n times.
{n,}: The preceding item is matched n or more times.
{,m}: The preceding item is matched at most m times. This is a GNU
extension.
{n,m}: The preceding item is matched at least n times, but not more than
m times.

Concatenation

Two regular expressions may be concatenated; the resulting regular
expression matches any string formed by concatenating two substrings that
respectively match the concatenated expressions.

Alternation

Two regular expressions may be joined by the infix operator
|; the resulting regular expression matches any string matching
either alternate expression.

Precedence

Repetition takes precedence over concatenation, which in turn
takes precedence over alternation. A whole expression may be enclosed in
parentheses to override these precedence rules and form a subexpression.

Back-references and Subexpressions

The back-reference n, where n is a single
digit, matches the substring previously matched by the nth
parenthesized subexpression of the regular expression.

Basic vs Extended Regular Expressions

In basic regular expressions the meta-characters ?,
+, {, |, (, and ) lose their special
meaning; instead use the backslashed versions ?, +,
{, |, (, and ).

EXIT STATUS

Normally the exit status is 0 if a line is selected, 1 if no lines
were selected, and 2 if an error occurred. However, if the -q or
—quiet or —silent is used and a line is selected, the exit
status is 0 even if an error occurred.

ENVIRONMENT

The behavior of grep is affected by the following
environment variables.

The locale for category LC_foo is specified by
examining the three environment variables LC_ALL,
LC_foo, LANG, in that order. The first of these
variables that is set specifies the locale. For example, if LC_ALL is
not set, but LC_MESSAGES is set to pt_BR, then the Brazilian
Portuguese locale is used for the LC_MESSAGES category. The C locale
is used if none of these environment variables are set, if the locale
catalog is not installed, or if grep was not compiled with national
language support (NLS). The shell command locale -a lists locales
that are currently available.

GREP_COLORS: Controls how the —color option highlights output. Its value is a
colon-separated list of capabilities that defaults to
ms=01;31:mc=01;31:sl=:cx=:fn=35:ln=32:bn=32:se=36 with the
rv and ne boolean capabilities omitted (i.e., false).
Supported capabilities are as follows.

sl=: SGR substring for whole selected lines (i.e., matching lines when the
-v command-line option is omitted, or non-matching lines when
-v is specified). If however the boolean rv capability and
the -v command-line option are both specified, it applies to
context matching lines instead. The default is empty (i.e., the terminal’s
default color pair).
cx=: SGR substring for whole context lines (i.e., non-matching lines when the
-v command-line option is omitted, or matching lines when -v
is specified). If however the boolean rv capability and the
-v command-line option are both specified, it applies to selected
non-matching lines instead. The default is empty (i.e., the terminal’s
default color pair).
rv: Boolean value that reverses (swaps) the meanings of the sl= and
cx= capabilities when the -v command-line option is
specified. The default is false (i.e., the capability is omitted).
mt=01;31: SGR substring for matching non-empty text in any matching line (i.e., a
selected line when the -v command-line option is omitted, or a
context line when -v is specified). Setting this is equivalent to
setting both ms= and mc= at once to the same value. The
default is a bold red text foreground over the current line
background.
ms=01;31: SGR substring for matching non-empty text in a selected line. (This is
only used when the -v command-line option is omitted.) The effect
of the sl= (or cx= if rv) capability remains active
when this kicks in. The default is a bold red text foreground over the
current line background.
mc=01;31: SGR substring for matching non-empty text in a context line. (This is only
used when the -v command-line option is specified.) The effect of
the cx= (or sl= if rv) capability remains active when
this kicks in. The default is a bold red text foreground over the current
line background.
fn=35: SGR substring for file names prefixing any content line. The default is a
magenta text foreground over the terminal’s default background.
ln=32: SGR substring for line numbers prefixing any content line. The default is
a green text foreground over the terminal’s default background.
bn=32: SGR substring for byte offsets prefixing any content line. The default is
a green text foreground over the terminal’s default background.
se=36: SGR substring for separators that are inserted between selected line
fields (:), between context line fields, (—), and between
groups of adjacent lines when nonzero context is specified (—).
The default is a cyan text foreground over the terminal’s default
background.
ne: Boolean value that prevents clearing to the end of line using Erase in
Line (EL) to Right (33[K) each time a colorized item ends. This is
needed on terminals on which EL is not supported. It is otherwise useful
on terminals for which the back_color_erase (bce) boolean
terminfo capability does not apply, when the chosen highlight colors do
not affect the background, or when EL is too slow or causes too much
flicker. The default is false (i.e., the capability is omitted).

Note that boolean capabilities have no =… part. They are
omitted (i.e., false) by default and become true when specified.

See the Select Graphic Rendition (SGR) section in the
documentation of the text terminal that is used for permitted values and
their meaning as character attributes. These substring values are integers
in decimal representation and can be concatenated with semicolons.
grep takes care of assembling the result into a complete SGR sequence
(33[…m). Common values to concatenate include 1 for
bold, 4 for underline, 5 for blink, 7 for inverse,
39 for default foreground color, 30 to 37 for
foreground colors, 90 to 97 for 16-color mode foreground
colors, 38;5;0 to 38;5;255 for 88-color and 256-color modes
foreground colors, 49 for default background color, 40 to
47 for background colors, 100 to 107 for 16-color mode
background colors, and 48;5;0 to 48;5;255 for 88-color and
256-color modes background colors.

LC_ALL,
LC_COLLATE, LANG: These variables specify the locale for the LC_COLLATE category,
which determines the collating sequence used to interpret range
expressions like [a-z].
LC_ALL,
LC_CTYPE, LANG: These variables specify the locale for the LC_CTYPE category, which
determines the type of characters, e.g., which characters are whitespace.
This category also determines the character encoding, that is, whether
text is encoded in UTF-8, ASCII, or some other encoding. In the C or POSIX
locale, all characters are encoded as a single byte and every byte is a
valid character.
LC_ALL,
LC_MESSAGES, LANG: These variables specify the locale for the LC_MESSAGES category,
which determines the language that grep uses for messages. The
default C locale uses American English messages.
POSIXLY_CORRECT: If set, grep behaves as POSIX requires; otherwise, grep
behaves more like other GNU programs. POSIX requires that options that
follow file names must be treated as file names; by default, such options
are permuted to the front of the operand list and are treated as options.
Also, POSIX requires that unrecognized options be diagnosed as
“illegal”, but since they are not really against the law the
default is to diagnose them as “invalid”.

NOTES

This man page is maintained only fitfully; the full documentation
is often more up-to-date.

COPYRIGHT

This is free software; see the source for copying conditions.
There is NO warranty; not even for MERCHANTABILITY or FITNESS FOR A
PARTICULAR PURPOSE.

BUGS

Reporting Bugs

Email bug reports to the bug-reporting address
⟨bug-grep@gnu.org⟩. An email archive
⟨https://lists.gnu.org/mailman/listinfo/bug-grep⟩ and a bug
tracker
⟨https://debbugs.gnu.org/cgi/pkgreport.cgi?package=grep⟩ are
available.

Known Bugs

Large repetition counts in the
{n,m} construct may cause grep to
use lots of memory. In addition, certain other obscure regular expressions
require exponential time and space, and may cause grep to run out of
memory.

Back-references are very slow, and may require exponential
time.

EXAMPLE

The following example outputs the location and contents of any
line containing “f” and ending in “.c”, within
all files in the current directory whose names contain “g” and
end in “.h”. The -n option outputs line numbers, the
— argument treats expansions of “*g*.h” starting with
“-” as file names not options, and the empty file /dev/null
causes file names to be output even if only one file name happens to be of
the form “*g*.h”.

$ grep -n -- 'f.*.c$' *g*.h /dev/null
argmatch.h:1:/* definitions and prototypes for argmatch.c

The only line that matches is line 1 of argmatch.h. Note that the
regular expression syntax used in the pattern differs from the globbing
syntax that the shell uses to match file names.

Regular Manual Pages

awk(1), cmp(1), diff(1), find(1),
perl(1), sed(1), sort(1), xargs(1),
read(2), pcre2(3), pcre2syntax(3),
pcre2pattern(3), terminfo(5), glob(7),
regex(7)

Full Documentation

A complete manual
⟨https://www.gnu.org/software/grep/manual/⟩ is available. If
the info and grep programs are properly installed at your
site, the command

info grep

should give you access to the complete manual.

Источник

grep — Man Page

print lines that match patterns

Examples (TL;DR)

Search for a pattern within a file: grep "search_pattern" path/to/file
Search for an exact string (disables regular expressions): grep --fixed-strings "exact_string" path/to/file
Search for a pattern in all files recursively in a directory, showing line numbers of matches, ignoring binary files: grep --recursive --line-number --binary-files=without-match "search_pattern" path/to/directory
Use extended regular expressions (supports ?, +, {}, () and |), in case-insensitive mode: grep --extended-regexp --ignore-case "search_pattern" path/to/file
Print 3 lines of context around, before, or after each match: grep --context|before-context|after-context=3 "search_pattern" path/to/file
Print file name and line number for each match with color output: grep --with-filename --line-number --color=always "search_pattern" path/to/file
Search for lines matching a pattern, printing only the matched text: grep --only-matching "search_pattern" path/to/file
Search stdin for lines that do not match a pattern: cat path/to/file | grep --invert-match "search_pattern"

tldr.sh

Synopsis

grep [OPTION...] PATTERNS [FILE...] grep [OPTION...] -e PATTERNS ... [FILE...] grep [OPTION...] -f PATTERN_FILE ... [FILE...]

Description

grep searches for PATTERNS in each FILE. PATTERNS is one or more patterns separated by newline characters, and grep prints each line that matches a pattern. Typically PATTERNS should be quoted when grep is used in a shell command.

A FILE of “—” stands for standard input. If no FILE is given, recursive searches examine the working directory, and nonrecursive searches read standard input.

Options

Generic Program Information

—help: Output a usage message and exit.
-V, —version: Output the version number of grep and exit.

Pattern Syntax

-E, —extended-regexp: Interpret PATTERNS as extended regular expressions (EREs, see below).
-F, —fixed-strings: Interpret PATTERNS as fixed strings, not regular expressions.
-G, —basic-regexp: Interpret PATTERNS as basic regular expressions (BREs, see below). This is the default.
-P, —perl-regexp: Interpret PATTERNS as Perl-compatible regular expressions (PCREs). This option is experimental when combined with the -z (—null-data) option, and grep -P may warn of unimplemented features.

Matching Control

-e PATTERNS, —regexp=PATTERNS: Use PATTERNS as the patterns. If this option is used multiple times or is combined with the -f (—file) option, search for all patterns given. This option can be used to protect a pattern beginning with “-”.
-f FILE, —file=FILE: Obtain patterns from FILE, one per line. If this option is used multiple times or is combined with the -e (—regexp) option, search for all patterns given. The empty file contains zero patterns, and therefore matches nothing.
-i, —ignore-case: Ignore case distinctions in patterns and input data, so that characters that differ only in case match each other.
—no-ignore-case: Do not ignore case distinctions in patterns and input data. This is the default. This option is useful for passing to shell scripts that already use -i, to cancel its effects because the two options override each other.
-v, —invert-match: Invert the sense of matching, to select non-matching lines.
-w, —word-regexp: Select only those lines containing matches that form whole words. The test is that the matching substring must either be at the beginning of the line, or preceded by a non-word constituent character. Similarly, it must be either at the end of the line or followed by a non-word constituent character. Word-constituent characters are letters, digits, and the underscore. This option has no effect if -x is also specified.
-x, —line-regexp: Select only those matches that exactly match the whole line. For a regular expression pattern, this is like parenthesizing the pattern and then surrounding it with ^ and $.

General Output Control

-c, —count: Suppress normal output; instead print a count of matching lines for each input file. With the -v, —invert-match option (see above), count non-matching lines.
—color[=WHEN], —colour[=WHEN]: Surround the matched (non-empty) strings, matching lines, context lines, file names, line numbers, byte offsets, and separators (for fields and groups of context lines) with escape sequences to display them in color on the terminal. The colors are defined by the environment variable GREP_COLORS. WHEN is never, always, or auto.
-L, —files-without-match: Suppress normal output; instead print the name of each input file from which no output would normally have been printed.
-l, —files-with-matches: Suppress normal output; instead print the name of each input file from which output would normally have been printed. Scanning each input file stops upon first match.
-m NUM, —max-count=NUM: Stop reading a file after NUM matching lines. If NUM is zero, grep stops right away without reading input. A NUM of -1 is treated as infinity and grep does not stop; this is the default. If the input is standard input from a regular file, and NUM matching lines are output, grep ensures that the standard input is positioned to just after the last matching line before exiting, regardless of the presence of trailing context lines. This enables a calling process to resume a search. When grep stops after NUM matching lines, it outputs any trailing context lines. When the -c or —count option is also used, grep does not output a count greater than NUM. When the -v or —invert-match option is also used, grep stops after outputting NUM non-matching lines.
-o, —only-matching: Print only the matched (non-empty) parts of a matching line, with each such part on a separate output line.
-q, —quiet, —silent: Quiet; do not write anything to standard output. Exit immediately with zero status if any match is found, even if an error was detected. Also see the -s or —no-messages option.
-s, —no-messages: Suppress error messages about nonexistent or unreadable files.

Output Line Prefix Control

-b, —byte-offset: Print the 0-based byte offset within the input file before each line of output. If -o (—only-matching) is specified, print the offset of the matching part itself.
-H, —with-filename: Print the file name for each match. This is the default when there is more than one file to search. This is a GNU extension.
-h, —no-filename: Suppress the prefixing of file names on output. This is the default when there is only one file (or only standard input) to search.
—label=LABEL: Display input actually coming from standard input as input coming from file LABEL. This can be useful for commands that transform a file’s contents before searching, e.g., gzip -cd foo.gz | grep —label=foo -H ‘some pattern’. See also the -H option.
-n, —line-number: Prefix each line of output with the 1-based line number within its input file.
-T, —initial-tab: Make sure that the first character of actual line content lies on a tab stop, so that the alignment of tabs looks normal. This is useful with options that prefix their output to the actual content: -H,-n, and -b. In order to improve the probability that lines from a single file will all start at the same column, this also causes the line number and byte offset (if present) to be printed in a minimum size field width.
-Z, —null: Output a zero byte (the ASCII NUL character) instead of the character that normally follows a file name. For example, grep -lZ outputs a zero byte after each file name instead of the usual newline. This option makes the output unambiguous, even in the presence of file names containing unusual characters like newlines. This option can be used with commands like find -print0, perl -0, sort -z, and xargs -0 to process arbitrary file names, even those that contain newline characters.

Context Line Control

-A NUM, —after-context=NUM: Print NUM lines of trailing context after matching lines. Places a line containing a group separator (—) between contiguous groups of matches. With the -o or —only-matching option, this has no effect and a warning is given.
-B NUM, —before-context=NUM: Print NUM lines of leading context before matching lines. Places a line containing a group separator (—) between contiguous groups of matches. With the -o or —only-matching option, this has no effect and a warning is given.
-C NUM, -NUM, —context=NUM: Print NUM lines of output context. Places a line containing a group separator (—) between contiguous groups of matches. With the -o or —only-matching option, this has no effect and a warning is given.
—group-separator=SEP: When -A, -B, or -C are in use, print SEP instead of — between groups of lines.
—no-group-separator: When -A, -B, or -C are in use, do not print a separator between groups of lines.

File and Directory Selection

-a, —text

Process a binary file as if it were text; this is equivalent to the —binary-files=text option.

—binary-files=TYPE

If a file’s data or metadata indicate that the file contains binary data, assume that the file is of type TYPE. Non-text bytes indicate binary data; these are either output bytes that are improperly encoded for the current locale, or null input bytes when the -z option is not given.

By default, TYPE is binary, and grep suppresses output after null input binary data is discovered, and suppresses output lines that contain improperly encoded data. When some output is suppressed, grep follows any output with a message to standard error saying that a binary file matches.

If TYPE is without-match, when grep discovers null input binary data it assumes that the rest of the file does not match; this is equivalent to the -I option.

If TYPE is text, grep processes a binary file as if it were text; this is equivalent to the -a option.

When type is binary, grep may treat non-text bytes as line terminators even without the -z option. This means choosing binary versus text can affect whether a pattern matches a file. For example, when type is binary the pattern q$ might match q immediately followed by a null byte, even though this is not matched when type is text. Conversely, when type is binary the pattern . (period) might not match a null byte.

Warning: The -a option might output binary garbage, which can have nasty side effects if the output is a terminal and if the terminal driver interprets some of it as commands. On the other hand, when reading files whose text encodings are unknown, it can be helpful to use -a or to set LC_ALL=’C’ in the environment, in order to find more matches even if the matches are unsafe for direct display.

-D ACTION, —devices=ACTION

If an input file is a device, FIFO or socket, use ACTION to process it. By default, ACTION is read, which means that devices are read just as if they were ordinary files. If ACTION is skip, devices are silently skipped.

-d ACTION, —directories=ACTION

If an input file is a directory, use ACTION to process it. By default, ACTION is read, i.e., read directories just as if they were ordinary files. If ACTION is skip, silently skip directories. If ACTION is recurse, read all files under each directory, recursively, following symbolic links only if they are on the command line. This is equivalent to the -r option.

—exclude=GLOB

Skip any command-line file with a name suffix that matches the pattern GLOB, using wildcard matching; a name suffix is either the whole name, or a trailing part that starts with a non-slash character immediately after a slash (/) in the name. When searching recursively, skip any subfile whose base name matches GLOB; the base name is the part after the last slash. A pattern can use *, ?, and […] as wildcards, and to quote a wildcard or backslash character literally.

—exclude-from=FILE

Skip files whose base name matches any of the file-name globs read from FILE (using wildcard matching as described under —exclude).

—exclude-dir=GLOB

Skip any command-line directory with a name suffix that matches the pattern GLOB. When searching recursively, skip any subdirectory whose base name matches GLOB. Ignore any redundant trailing slashes in GLOB.

-I

Process a binary file as if it did not contain matching data; this is equivalent to the —binary-files=without-match option.

—include=GLOB

Search only files whose base name matches GLOB (using wildcard matching as described under —exclude). If contradictory —include and —exclude options are given, the last matching one wins. If no —include or —exclude options match, a file is included unless the first such option is —include.

-r, —recursive

Read all files under each directory, recursively, following symbolic links only if they are on the command line. Note that if no file operand is given, grep searches the working directory. This is equivalent to the -d recurse option.

-R, —dereference-recursive

Read all files under each directory, recursively. Follow all symbolic links, unlike -r.

Other Options

—line-buffered: Use line buffering on output. This can cause a performance penalty.
-U, —binary: Treat the file(s) as binary. By default, under MS-DOS and MS-Windows, grep guesses whether a file is text or binary as described for the —binary-files option. If grep decides the file is a text file, it strips the CR characters from the original file contents (to make regular expressions with ^ and $ work correctly). Specifying -U overrules this guesswork, causing all files to be read and passed to the matching mechanism verbatim; if the file is a text file with CR/LF pairs at the end of each line, this will cause some regular expressions to fail. This option has no effect on platforms other than MS-DOS and MS-Windows.
-z, —null-data: Treat input and output data as sequences of lines, each terminated by a zero byte (the ASCII NUL character) instead of a newline. Like the -Z or —null option, this option can be used with commands like sort -z to process arbitrary file names.

Regular Expressions

A regular expression is a pattern that describes a set of strings. Regular expressions are constructed analogously to arithmetic expressions, by using various operators to combine smaller expressions.

grep understands three different versions of regular expression syntax: “basic” (BRE), “extended” (ERE) and “perl” (PCRE). In GNU grep there is no difference in available functionality between basic and extended syntax. In other implementations, basic regular expressions are less powerful. The following description applies to extended regular expressions; differences for basic regular expressions are summarized afterwards. Perl-compatible regular expressions give additional functionality, and are documented in pcre2syntax(3) and pcre2pattern(3), but work only if PCRE support is enabled.

The fundamental building blocks are the regular expressions that match a single character. Most characters, including all letters and digits, are regular expressions that match themselves. Any meta-character with special meaning may be quoted by preceding it with a backslash.

The period . matches any single character. It is unspecified whether it matches an encoding error.

Character Classes and Bracket Expressions

A bracket expression is a list of characters enclosed by [ and ]. It matches any single character in that list. If the first character of the list is the caret ^ then it matches any character not in the list; it is unspecified whether it matches an encoding error. For example, the regular expression [0123456789] matches any single digit.

Within a bracket expression, a range expression consists of two characters separated by a hyphen. It matches any single character that sorts between the two characters, inclusive, using the locale’s collating sequence and character set. For example, in the default C locale, [a-d] is equivalent to [abcd]. Many locales sort characters in dictionary order, and in these locales [a-d] is typically not equivalent to [abcd]; it might be equivalent to [aBbCcDd], for example. To obtain the traditional interpretation of bracket expressions, you can use the C locale by setting the LC_ALL environment variable to the value C.

Finally, certain named classes of characters are predefined within bracket expressions, as follows. Their names are self explanatory, and they are [:alnum:], [:alpha:], [:blank:], [:cntrl:], [:digit:], [:graph:], [:lower:], [:print:], [:punct:], [:space:], [:upper:], and [:xdigit:]. For example, [[:alnum:]] means the character class of numbers and letters in the current locale. In the C locale and ASCII character set encoding, this is the same as [0-9A-Za-z]. (Note that the brackets in these class names are part of the symbolic names, and must be included in addition to the brackets delimiting the bracket expression.) Most meta-characters lose their special meaning inside bracket expressions. To include a literal ] place it first in the list. Similarly, to include a literal ^ place it anywhere but first. Finally, to include a literal — place it last.

Anchoring

The caret ^ and the dollar sign $ are meta-characters that respectively match the empty string at the beginning and end of a line.

The Backslash Character and Special Expressions

The symbols < and > respectively match the empty string at the beginning and end of a word. The symbol b matches the empty string at the edge of a word, and B matches the empty string provided it’s not at the edge of a word. The symbol w is a synonym for [_[:alnum:]] and W is a synonym for [^_[:alnum:]].

Repetition

A regular expression may be followed by one of several repetition operators:

?: The preceding item is optional and matched at most once.
*: The preceding item will be matched zero or more times.
+: The preceding item will be matched one or more times.
{n}: The preceding item is matched exactly n times.
{n,}: The preceding item is matched n or more times.
{,m}: The preceding item is matched at most m times. This is a GNU extension.
{n,m}: The preceding item is matched at least n times, but not more than m times.

Concatenation

Two regular expressions may be concatenated; the resulting regular expression matches any string formed by concatenating two substrings that respectively match the concatenated expressions.

Alternation

Two regular expressions may be joined by the infix operator |; the resulting regular expression matches any string matching either alternate expression.

Precedence

Repetition takes precedence over concatenation, which in turn takes precedence over alternation. A whole expression may be enclosed in parentheses to override these precedence rules and form a subexpression.

Back-references and Subexpressions

The back-reference n, where n is a single digit, matches the substring previously matched by the nth parenthesized subexpression of the regular expression.

Basic vs Extended Regular Expressions

In basic regular expressions the meta-characters ?, +, {, |, (, and ) lose their special meaning; instead use the backslashed versions ?, +, {, |, (, and ).

Exit Status

Normally the exit status is 0 if a line is selected, 1 if no lines were selected, and 2 if an error occurred. However, if the -q or —quiet or —silent is used and a line is selected, the exit status is 0 even if an error occurred.

Environment

The behavior of grep is affected by the following environment variables.

The locale for category LC_foo is specified by examining the three environment variables LC_ALL, LC_foo, LANG, in that order. The first of these variables that is set specifies the locale. For example, if LC_ALL is not set, but LC_MESSAGES is set to pt_BR, then the Brazilian Portuguese locale is used for the LC_MESSAGES category. The C locale is used if none of these environment variables are set, if the locale catalog is not installed, or if grep was not compiled with national language support (NLS). The shell command locale -a lists locales that are currently available.

GREP_COLORS

Controls how the —color option highlights output. Its value is a colon-separated list of capabilities that defaults to ms=01;31:mc=01;31:sl=:cx=:fn=35:ln=32:bn=32:se=36 with the rv and ne boolean capabilities omitted (i.e., false). Supported capabilities are as follows.

sl=: SGR substring for whole selected lines (i.e., matching lines when the -v command-line option is omitted, or non-matching lines when -v is specified). If however the boolean rv capability and the -v command-line option are both specified, it applies to context matching lines instead. The default is empty (i.e., the terminal’s default color pair).
cx=: SGR substring for whole context lines (i.e., non-matching lines when the -v command-line option is omitted, or matching lines when -v is specified). If however the boolean rv capability and the -v command-line option are both specified, it applies to selected non-matching lines instead. The default is empty (i.e., the terminal’s default color pair).
rv: Boolean value that reverses (swaps) the meanings of the sl= and cx= capabilities when the -v command-line option is specified. The default is false (i.e., the capability is omitted).
mt=01;31: SGR substring for matching non-empty text in any matching line (i.e., a selected line when the -v command-line option is omitted, or a context line when -v is specified). Setting this is equivalent to setting both ms= and mc= at once to the same value. The default is a bold red text foreground over the current line background.
ms=01;31: SGR substring for matching non-empty text in a selected line. (This is only used when the -v command-line option is omitted.) The effect of the sl= (or cx= if rv) capability remains active when this kicks in. The default is a bold red text foreground over the current line background.
mc=01;31: SGR substring for matching non-empty text in a context line. (This is only used when the -v command-line option is specified.) The effect of the cx= (or sl= if rv) capability remains active when this kicks in. The default is a bold red text foreground over the current line background.
fn=35: SGR substring for file names prefixing any content line. The default is a magenta text foreground over the terminal’s default background.
ln=32: SGR substring for line numbers prefixing any content line. The default is a green text foreground over the terminal’s default background.
bn=32: SGR substring for byte offsets prefixing any content line. The default is a green text foreground over the terminal’s default background.
se=36: SGR substring for separators that are inserted between selected line fields (:), between context line fields, (—), and between groups of adjacent lines when nonzero context is specified (—). The default is a cyan text foreground over the terminal’s default background.
ne: Boolean value that prevents clearing to the end of line using Erase in Line (EL) to Right (33[K) each time a colorized item ends. This is needed on terminals on which EL is not supported. It is otherwise useful on terminals for which the back_color_erase (bce) boolean terminfo capability does not apply, when the chosen highlight colors do not affect the background, or when EL is too slow or causes too much flicker. The default is false (i.e., the capability is omitted).

Note that boolean capabilities have no =… part. They are omitted (i.e., false) by default and become true when specified.

See the Select Graphic Rendition (SGR) section in the documentation of the text terminal that is used for permitted values and their meaning as character attributes. These substring values are integers in decimal representation and can be concatenated with semicolons. grep takes care of assembling the result into a complete SGR sequence (33[…m). Common values to concatenate include 1 for bold, 4 for underline, 5 for blink, 7 for inverse, 39 for default foreground color, 30 to 37 for foreground colors, 90 to 97 for 16-color mode foreground colors, 38;5;0 to 38;5;255 for 88-color and 256-color modes foreground colors, 49 for default background color, 40 to 47 for background colors, 100 to 107 for 16-color mode background colors, and 48;5;0 to 48;5;255 for 88-color and 256-color modes background colors.

LC_ALL, LC_COLLATE, LANG

These variables specify the locale for the LC_COLLATE category, which determines the collating sequence used to interpret range expressions like [a-z].

LC_ALL, LC_CTYPE, LANG

These variables specify the locale for the LC_CTYPE category, which determines the type of characters, e.g., which characters are whitespace. This category also determines the character encoding, that is, whether text is encoded in UTF-8, ASCII, or some other encoding. In the C or POSIX locale, all characters are encoded as a single byte and every byte is a valid character.

LC_ALL, LC_MESSAGES, LANG

These variables specify the locale for the LC_MESSAGES category, which determines the language that grep uses for messages. The default C locale uses American English messages.

POSIXLY_CORRECT

If set, grep behaves as POSIX requires; otherwise, grep behaves more like other GNU programs. POSIX requires that options that follow file names must be treated as file names; by default, such options are permuted to the front of the operand list and are treated as options. Also, POSIX requires that unrecognized options be diagnosed as “illegal”, but since they are not really against the law the default is to diagnose them as “invalid”. POSIXLY_CORRECT also disables _N_GNU_nonoption_argv_flags_, described below.

_N_GNU_nonoption_argv_flags_

(Here N is grep‘s numeric process ID.) If the ith character of this environment variable’s value is 1, do not consider the ith operand of grep to be an option, even if it appears to be one. A shell can put this variable in the environment for each command it runs, specifying which operands are the results of file name wildcard expansion and therefore should not be treated as options. This behavior is available only with the GNU C library, and only when POSIXLY_CORRECT is not set.

Notes

This man page is maintained only fitfully; the full documentation is often more up-to-date.

Copyright

This is free software; see the source for copying conditions. There is NO warranty; not even for MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.

Bugs

Reporting Bugs

Email bug reports to the bug-reporting address ⟨bug-grep@gnu.org⟩. An email archive ⟨https://lists.gnu.org/mailman/listinfo/bug-grep⟩ and a bug tracker ⟨https://debbugs.gnu.org/cgi/pkgreport.cgi?package=grep⟩ are available.

Known Bugs

Large repetition counts in the {n,m} construct may cause grep to use lots of memory. In addition, certain other obscure regular expressions require exponential time and space, and may cause grep to run out of memory.

Back-references are very slow, and may require exponential time.

Example

The following example outputs the location and contents of any line containing “f” and ending in “.c”, within all files in the current directory whose names contain “g” and end in “.h”. The -n option outputs line numbers, the — argument treats expansions of “*g*.h” starting with “-” as file names not options, and the empty file /dev/null causes file names to be output even if only one file name happens to be of the form “*g*.h”.

$ grep -n -- 'f.*.c$' *g*.h /dev/null
argmatch.h:1:/* definitions and prototypes for argmatch.c

The only line that matches is line 1 of argmatch.h. Note that the regular expression syntax used in the pattern differs from the globbing syntax that the shell uses to match file names.

Referenced By

ag(1), bournal(1), bridge(8), bz3grep(1), bzgrep(1), cdist-type__pacman_conf(7), cdist-type__pacman_conf_integrate(7), flowdumper(1), fmidi-grep(1), fortune(6), fpart(1), getbuildlog(1), global(1), grepmail(1), guestfish(1), guestfs(3), ip(8), ksh93(1), lbzgrep(1), libinn_uwildmat(3), libxo(3), look(1), maildrop(1), maildropex(7), makeindex(1), makemime(1), mate-search-tool(1), mawk(1), mksh(1), mle(1), nawk(1), oksh(1), pass(1), patool(1), pdfgrep(1), pdsh(1), perlfunc(1), pick(1), pmrep(1), procmail(1), procmailex(5), procmailrc(5), procmailsc(5), pwqfilter(1), quilt(1), ragrep(1), reformime(1), regex(3), regex(7), ronn(1), ronn-format(7), sed(1), sudoers(5), tc(8), trace-cmd-record(1), trace-cmd-set(1), ugrep(1), xzgrep(1), zgrep(1), zstdgrep(1).

2019-12-29 GNU grep 3.9

Источник

Problem:

Solution:

Conclusion:

Short answer

Explained

[additional] usage in shell scripts

[additional] ps + grep

NAME

SYNOPSIS

DESCRIPTION

OPTIONS

Generic Program Information

Pattern Syntax

Matching Control

General Output Control

Output Line Prefix Control

Context Line Control

File and Directory Selection

Other Options

REGULAR EXPRESSIONS

Character Classes and Bracket Expressions

Anchoring

The Backslash Character and Special Expressions

Repetition

Concatenation

Alternation

Precedence

Back-references and Subexpressions

Basic vs Extended Regular Expressions

EXIT STATUS

ENVIRONMENT

NOTES

COPYRIGHT

BUGS

Reporting Bugs

Known Bugs

EXAMPLE

SEE ALSO

Regular Manual Pages

Full Documentation

Examples (TL;DR)

Synopsis

Description

Options

Generic Program Information

Pattern Syntax

Matching Control

General Output Control

Output Line Prefix Control

Context Line Control

File and Directory Selection

Other Options

Regular Expressions

Character Classes and Bracket Expressions

Anchoring

The Backslash Character and Special Expressions

Repetition

Concatenation

Alternation

Precedence

Back-references and Subexpressions

Basic vs Extended Regular Expressions

Exit Status

Environment

Notes

Copyright

Bugs

Reporting Bugs

Known Bugs

Example

See Also

Regular Manual Pages

Full Documentation

Referenced By

[additional] `ps` + `grep`