GREP(1)GREP(1)NAME
grep - search a file for a pattern
SYNOPSIS
/usr/bin/grep [-c | -l |-q] [-r | -R] [-bHhinsvw]
limited-regular-expression [filename]...
/usr/xpg4/bin/grep [-E | -F] [-c | -l | -q] [-r | -R]
[-bHhinsvwx] -e pattern_list... [-f pattern_file]...
[file]...
/usr/xpg4/bin/grep [-E | -F] [-c | -l | -q] [-r | -R]
[-bHhinsvwx] [-e pattern_list]... -f pattern_file...
[file]...
/usr/xpg4/bin/grep [-E | -F] [-c | -l | -q] [-r | -R]
[-bHhinsvwx] pattern [file]...
DESCRIPTION
The grep utility searches text files for a pattern and prints all lines
that contain that pattern. It uses a compact non-deterministic algo‐
rithm.
Be careful using the characters $, *, [, ^, |, (, ), and \ in the pat‐
tern_list because they are also meaningful to the shell. It is safest
to enclose the entire pattern_list in single quotes a´...a´.
If no files are specified, grep assumes standard input. Normally, each
line found is copied to standard output. The file name is printed
before each line found if there is more than one input file.
/usr/bin/grep
The /usr/bin/grep utility uses limited regular expressions like those
described on the regexp(5) manual page to match the patterns.
/usr/xpg4/bin/grep
The options -E and -F affect the way /usr/xpg4/bin/grep interprets pat‐
tern_list. If -E is specified, /usr/xpg4/bin/grep interprets pat‐
tern_list as a full regular expression (see -E for description). If -F
is specified, grep interprets pattern_list as a fixed string. If nei‐
ther are specified, grep interprets pattern_list as a basic regular
expression as described on regex(5) manual page.
OPTIONS
The following options are supported for both /usr/bin/grep and
/usr/xpg4/bin/grep:
-b
Precedes each line by the block number on which it was found.
This can be useful in locating block numbers by context (first
block is 0).
-c
Prints only a count of the lines that contain the pattern.
-H
Precedes each line by the name of the file containing the match‐
ing line.
-h
Prevents the name of the file containing the matching line from
being prepended to that line. Used when searching multiple
files.
-i
Ignores upper/lower case distinction during comparisons.
-l
Prints only the names of files with matching lines, separated by
NEWLINE characters. Does not repeat the names of files when the
pattern is found more than once.
-n
Precedes each line by its line number in the file (first line is
1).
-r
Read all files under each directory, recursively. Follow symbolic
links on the command line, but skip symlinks that are encountered
recursively. If file is a device, FIFO, or socket, skip it.
-R
Read all files under each directory, recursively, following all
symbolic links.
-q
Quiet. Does not write anything to the standard output, regardless
of matching lines. Exits with zero status if an input line is
selected.
-s
Suppresses error messages about nonexistent or unreadable files.
-v
Prints all lines except those that contain the pattern.
-w
Searches for the expression as a word as if surrounded by \< and
\>.
/usr/xpg4/bin/grep
The following options are supported for /usr/xpg4/bin/grep only:
-e pattern_list
Specifies one or more patterns to be used during the
search for input. Patterns in pattern_list must be
separated by a NEWLINE character. A null pattern can
be specified by two adjacent newline characters in
pattern_list. Unless the -E or -F option is also
specified, each pattern is treated as a basic regu‐
lar expression. Multiple -e and -f options are
accepted by grep. All of the specified patterns are
used when matching lines, but the order of evalua‐
tion is unspecified.
-E
Matches using full regular expressions. Treats each
pattern specified as a full regular expression. If
any entire full regular expression pattern matches
an input line, the line is matched. A null full reg‐
ular expression matches every line. Each pattern is
interpreted as a full regular expression as
described on the regex(5) manual page, except for \(
and \), and including:
1. A full regular expression followed by +
that matches one or more occurrences of
the full regular expression.
2. A full regular expression followed by ?
that matches 0 or 1 occurrences of the
full regular expression.
3. Full regular expressions separated by |
or by a new-line that match strings that
are matched by any of the expressions.
4. A full regular expression that is
enclosed in parentheses () for grouping.
The order of precedence of operators is [], then
*?+, then concatenation, then | and new-line.
-f pattern_file
Reads one or more patterns from the file named by
the path name pattern_file. Patterns in pattern_file
are terminated by a NEWLINE character. A null pat‐
tern can be specified by an empty line in pat‐
tern_file. Unless the -E or -F option is also speci‐
fied, each pattern is treated as a basic regular
expression.
-F
Matches using fixed strings. Treats each pattern
specified as a string instead of a regular expres‐
sion. If an input line contains any of the patterns
as a contiguous sequence of bytes, the line is
matched. A null string matches every line. See
fgrep(1) for more information.
-x
Considers only input lines that use all characters
in the line to match an entire fixed string or regu‐
lar expression to be matching lines.
OPERANDS
The following operands are supported:
file
A path name of a file to be searched for the patterns. If no
file operands are specified, the standard input is used.
/usr/bin/grep
pattern
Specifies a pattern to be used during the search for input.
/usr/xpg4/bin/grep
pattern
Specifies one or more patterns to be used during the search
for input. This operand is treated as if it were specified
as -e pattern_list.
USAGE
The -e pattern_list option has the same effect as the pattern_list op‐
erand, but is useful when pattern_list begins with the hyphen delim‐
iter. It is also useful when it is more convenient to provide multiple
patterns as separate arguments.
Multiple -e and -f options are accepted and grep uses all of the pat‐
terns it is given while matching input text lines. Notice that the
order of evaluation is not specified. If an implementation finds a null
string as a pattern, it is allowed to use that pattern first, matching
every line, and effectively ignore any other patterns.
The -q option provides a means of easily determining whether or not a
pattern (or string) exists in a group of files. When searching several
files, it provides a performance improvement (because it can quit as
soon as it finds the first match) and requires less care by the user in
choosing the set of files to supply as arguments (because it exits zero
if it finds a match even if grep detected an access or read error on
earlier file operands).
Large File Behavior
See largefile(5) for the description of the behavior of grep when
encountering files greater than or equal to 2 Gbyte ( 2^31 bytes).
EXAMPLES
Example 1 Finding All Uses of a Word
To find all uses of the word "Posix" (in any case) in the file text.mm,
and write with line numbers:
example% /usr/bin/grep -i -n posix text.mm
Example 2 Finding All Empty Lines
To find all empty lines in the standard input:
example% /usr/bin/grep ^$
or
example% /usr/bin/grep -v .
Example 3 Finding Lines Containing Strings
All of the following commands print all lines containing strings abc or
def or both:
example% /usr/xpg4/bin/grep 'abc
def'
example% /usr/xpg4/bin/grep -e 'abc
def'
example% /usr/xpg4/bin/grep -e 'abc' -e 'def'
example% /usr/xpg4/bin/grep -E 'abc|def'
example% /usr/xpg4/bin/grep -E -e 'abc|def'
example% /usr/xpg4/bin/grep -E -e 'abc' -e 'def'
example% /usr/xpg4/bin/grep -E 'abc
def'
example% /usr/xpg4/bin/grep -E -e 'abc
def'
example% /usr/xpg4/bin/grep -F -e 'abc' -e 'def'
example% /usr/xpg4/bin/grep -F 'abc
def'
example% /usr/xpg4/bin/grep -F -e 'abc
def'
Example 4 Finding Lines with Matching Strings
Both of the following commands print all lines matching exactly abc or
def:
example% /usr/xpg4/bin/grep -E '^abc$ ^def$'
example% /usr/xpg4/bin/grep -F -x 'abc def'
ENVIRONMENT VARIABLES
See environ(5) for descriptions of the following environment variables
that affect the execution of grep: LANG, LC_ALL, LC_COLLATE, LC_CTYPE,
LC_MESSAGES, and NLSPATH.
EXIT STATUS
The following exit values are returned:
0
One or more matches were found.
1
No matches were found.
2
Syntax errors or inaccessible files (even if matches were found).
ATTRIBUTES
See attributes(5) for descriptions of the following attributes:
/usr/bin/grep
┌───────────────┬─────────────────┐
│ATTRIBUTE TYPE │ ATTRIBUTE VALUE │
├───────────────┼─────────────────┤
│CSI │ Not Enabled │
└───────────────┴─────────────────┘
/usr/xpg4/bin/grep
┌────────────────────┬───────────────────┐
│ ATTRIBUTE TYPE │ ATTRIBUTE VALUE │
├────────────────────┼───────────────────┤
│CSI │ Enabled │
├────────────────────┼───────────────────┤
│Interface Stability │ Committed │
├────────────────────┼───────────────────┤
│Standard │ See standards(5). │
└────────────────────┴───────────────────┘
SEE ALSOegrep(1), fgrep(1), sed(1), sh(1), attributes(5), environ(5), large‐
file(5), regex(5), regexp(5), standards(5)NOTES
/usr/bin/grep
Lines are limited only by the size of the available virtual memory. If
there is a line with embedded nulls, grep only matches up to the first
null. If the line matches, the entire line is printed.
/usr/xpg4/bin/grep
The results are unspecified if input files contain lines longer than
LINE_MAX bytes or contain binary data. LINE_MAX is defined in
/usr/include/limits.h.
May 3, 2013 GREP(1)
