Manual Pages for UNIX Operating System command usage for man fgrep
User Commands GREP(1)
NAME
grep, egrep, fgrep - print lines matching a pattern
SYNOPSIS
grep [OPTIONS] PATTERN [FILE...]
grep [OPTIONS] [-e PATTERN | -f FILE] [FILE...]
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, two variant programs egrep and fgrep are
available. egrep is the same as grep -E. fgrep is the same
as grep -F. 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. This
is highly experimental and grep -P may warn of
unimplemented features.
Matching Control
-e PATTERN, --regexp=PATTERN
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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[
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.
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User Commands GREP(1)
-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
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User Commands GREP(1)
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
for tools like zgrep, e.g., gzip -cd foo.gz | grep --
label=foo something
-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.
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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, which means that
directories are read just as if they were ordinary
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files. If ACTION is skip, directories are silently
skipped. If ACTION is recurse, grep reads all files
under each directory, recursively; 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, -r, --recursive
Read all files under each directory, recursively; this
is equivalent to the -d recurse option.
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).
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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.
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 two different versions of regular
expression syntax: "basic" and "extended." In GNU grep,
there is no difference in available functionality using
either 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.
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
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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 [0-9A-Za-z], except the latter
form depends upon the C locale and the ASCII character
encoding, whereas the former is independent of locale and
character set. (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.
{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.
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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.
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
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--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
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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
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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
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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
Normally, the exit status is 0 if selected lines are found
and 1 otherwise. But the exit status is 2 if an error
occurred, unless the -q or --quiet or --silent option is
used and a selected line is found. Note, however, that
POSIX only mandates, for programs such as grep, cmp, and
diff, that the exit status in case of error be greater than
1; it is therefore advisable, for the sake of portability,
to use logic that tests for this general condition instead
of strict equality with 2.
COPYRIGHT
Copyright cO 1998, 1999, 2000, 2002, 2005 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.
BUGS
Reporting Bugs
Email bug reports to , a mailing list
whose web page is
. grep's
Savannah bug tracker is located at
.
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.
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SEE ALSO
Regular Manual Pages
awk(1), cmp(1), diff(1), find(1), gzip(1), perl(1), sed(1),
sort(1), xargs(1), zgrep(1), mmap(2), read(2), pcre(3),
pcrepattern(3), terminfo(5), glob(7), regex(7).
POSIX Programmer's Manual Page
grep(1p).
TeXinfo Documentation
The full documentation for grep is maintained as a TeXinfo
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.
NOTES
GNU's not Unix, but Unix is a beast; its plural form is
Unixen.
ATTRIBUTES
See attributes(5) for descriptions of the following
attributes:
_______________________________________
| ATTRIBUTE TYPE | ATTRIBUTE VALUE|
|____________________|__________________|_
| Availability | text/gnu-grep |
|____________________|__________________|_
| Interface Stability| Volatile |
|____________________|_________________|
NOTES
Source for ggrep is available on http://opensolaris.org.
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