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 I<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 $.
-y Obsolete synonym for -i.
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 below), 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. The deprecated environment variable
GREP_COLOR is still supported, but its setting does not
have priority. 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 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
one-line message 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, B<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.
