fgrep
, rgrep print lines matching a pattern
see also :
egrep - rgrep - awk - cmp - diff - find - gzip - perl - sed - sort - xargs - zgrep - grep
Synopsis
grep
[OPTIONS] PATTERN [FILE...]
grep [OPTIONS] [-e PATTERN |
-f FILE] [FILE...]
add an example, a script, a trick and tips
examples
source
alias fgrep='fgrep --exclude-dir=".svn"' # TODO: add .git
source
~/dev/phantomjs/bin/phantomjs neitui.js | fgrep
`date +%m-%d` |
fgrep å??京
description
grep
searches the named input FILEs (or standard input if
no files are named, or if a single hyphen-minus
(-) is given as file name) for lines containing
a match to the given PATTERN. By default, grep
prints the matching lines.
In addition,
three variant programs egrep, fgrep and rgrep
are available. egrep is the same as
grep -E. fgrep is the same as
grep -F. rgrep is the same as
grep -r. Direct invocation as either
egrep or fgrep is deprecated, but is provided
to allow historical applications that rely on them to run
unmodified.
options
Generic
Program Information
--help
Print a usage message briefly summarizing these
command-line options and the bug-reporting address, then
exit.
-V,
--version
Print the version number of
grep to the standard output stream. This version
number should be included in all bug reports (see
below).
Matcher
Selection
-E, --extended-regexp
Interpret PATTERN as an
extended regular expression (ERE, see below).
(-E is specified by POSIX .)
-F,
--fixed-strings
Interpret PATTERN as a
list of fixed strings, separated by newlines, any of which
is to be matched. (-F is specified by
POSIX .)
-G,
--basic-regexp
Interpret PATTERN as a
basic regular expression (BRE, see below). This is the
default.
-P,
--perl-regexp
Interpret PATTERN as a
Perl regular expression (PCRE, see below). This is highly
experimental and grep -P may warn of
unimplemented features.
Matching
Control
-e PATTERN,
--regexp=PATTERN
Use PATTERN as the
pattern. This can be used to specify multiple search
patterns, or to protect a pattern beginning with a hyphen
(-). (-e is specified by
POSIX .)
-f FILE,
--file=FILE
Obtain patterns from
FILE, one per line. The empty file contains zero
patterns, and therefore matches nothing. (-f is
specified by POSIX .)
-i,
--ignore-case
Ignore case distinctions in
both the PATTERN and the input files.
(-i is specified by POSIX .)
-v,
--invert-match
Invert the sense of matching,
to select non-matching lines. (-v is specified
by POSIX .)
-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.
-x,
--line-regexp
Select only those matches that
exactly match the whole line. (-x is specified
by POSIX .)
-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.
(-c is specified by POSIX .)
--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. The scanning will stop on the
first match.
-l,
--files-with-matches
Suppress normal output; instead
print the name of each input file from which output would
normally have been printed. The scanning will stop on the
first match. (-l is specified by
POSIX .)
-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. (-q is specified by
POSIX .)
-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 .)
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.
-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 is especially useful when implementing tools like
zgrep, e.g., gzip -cd foo.gz | grep --label=foo -H
something. See also the -H option.
-n,
--line-number
Prefix each line of output with
the 1-based line number within its input file.
(-n is specified by POSIX .)
-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.
-u,
--unix-byte-offsets
Report Unix-style byte offsets.
This switch causes grep to report byte offsets as if
the file were a Unix-style text file, i.e., with CR
characters stripped off. This will produce results identical
to running grep on a Unix machine. This option has no
effect unless -b option is also used; it has no
effect on platforms other than MS-DOS and
MS -Windows.
-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.
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 the first few bytes of a
file indicate that the file contains binary data, assume
that the file is of type TYPE. By default,
TYPE is binary, and grep normally
outputs either a one-line message saying that a binary file
matches, or no message if there is no match. If TYPE
is without-match, grep assumes that a binary
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. Warning:
grep --binary-files=text 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.
-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 files whose base name
matches GLOB (using wildcard matching). A file-name
glob 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=DIR
Exclude directories matching
the pattern DIR from recursive searches.
-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).
-r,
--recursive
Read all files under each
directory, recursively, following symbolic links only if
they are on the command line. 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.
--mmap
If possible, use the mmap(2) system call to read
input, instead of the default read(2) system call. In
some situations, --mmap yields better
performance. However, --mmap can cause
undefined behavior (including core dumps) if an input file
shrinks while grep is operating, or if an I/O error
occurs.
-U,
--binary
Treat the file(s) as binary. By
default, under MS-DOS and MS
-Windows, grep guesses the file type by looking at
the contents of the first 32KB read from the file. 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 the input as a set 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.
copyright
Copyright 1998-2000, 2002, 2005-2012 Free Software Foundation,
Inc.
This is free software; see the source for copying conditions.
There is NO warranty; not even for MERCHANTABILITY or FITNESS FOR
A PARTICULAR PURPOSE.
environment variables
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 ).
GREP_OPTIONS
This variable specifies default options to be placed in front of
any explicit options. For example, if GREP_OPTIONS is
'--binary-files=without-match --directories=skip',
grep behaves as if the two options
--binary-files=without-match and --directories=skip
had been specified before any explicit options. Option
specifications are separated by whitespace. A backslash escapes
the next character, so it can be used to specify an option
containing whitespace or a backslash.
GREP_COLOR
This variable specifies the color used to highlight matched
(non-empty) text. It is deprecated in favor of
GREP_COLORS, but still supported. The mt,
ms, and mc capabilities of GREP_COLORS have
priority over it. It can only specify the color used to highlight
the matching non-empty text in any matching line (a selected line
when the -v command-line option is omitted, or a context
line when -v is specified). The default is 01;31,
which means a bold red foreground text on the terminal’s default
background.
GREP_COLORS
Specifies the colors and other attributes used to highlight
various parts of the 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.
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.2 requires;
otherwise, grep behaves more like other GNU
programs. POSIX.2 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.2 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.
exit status
The exit status is 0 if selected lines are found, and 1 if not
found. If an error occurred the exit status is 2. (Note: POSIX
error handling code should check for ’2’ or greater.)
notes
This man page is maintained only fitfully; the full documentation
is often more up-to-date.
GNU ’s not Unix, but Unix is a beast; its plural
form is Unixen.
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”
(PRCE). In GNU grep, there is no
difference in available functionality between basic and extended
syntaxes. 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 regular expressions give
additional functionality, and are documented in pcresyntax(3) and
pcrepattern(3), but may not be available on every system.
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.
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. 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:],
[: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.
{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 \?,
\+, \{, \|, \(, and \).
Traditional egrep did not support the {
meta-character, and some egrep implementations support
\{ instead, so portable scripts should avoid { in
grep -E patterns and should use [{] to match a
literal {.
GNU grep -E attempts to support
traditional usage by assuming that { is not special if it
would be the start of an invalid interval specification. For
example, the command grep -E '{1' searches for
the two-character string {1 instead of reporting a syntax
error in the regular expression. POSIX.2 allows
this behavior as an extension, but portable scripts should avoid
it.
bugs
Reporting
Bugs
Email bug reports to <bug-grep[:at:]gnu[:dot:]org>,
a mailing list whose web page is
<http://lists.gnu.org/mailman/listinfo/bug-grep>.
grep’s Savannah bug tracker is located at
<http://savannah.gnu.org/bugs/?group=grep>.
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.
see also
Regular
Manual Pages
awk , cmp , diff , find , gzip , perl , sed ,
sort , xargs , zgrep , mmap, read, pcre,
pcresyntax, pcrepattern, terminfo, glob,
regex.
POSIX
Programmer’s Manual Page
grep (1p).
TeXinfo
Documentation
The full documentation for grep is maintained as a
TeXinfo manual, which you can read at
http://www.gnu.org/software/grep/manual/. If the info
and grep programs are properly installed at your
site, the command
info
grep
should give you
access to the complete manual.