GREP(1) User Commands 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
algorithm.


Be careful using the characters $, *, [, ^, |, (, ), and \ in the
pattern_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
pattern_list. If -E is specified, /usr/xpg4/bin/grep interprets
pattern_list as a full regular expression (see -E for description). If
-F is specified, grep interprets pattern_list as a fixed string. If
neither 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 matching
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 regular
expression. Multiple -e and -f options are accepted
by grep. All of the specified patterns are used when
matching lines, but the order of evaluation 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 regular
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 pattern can
be specified by an empty line in pattern_file. Unless
the -E or -F option is also specified, 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 expression.
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 regular
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
operand, but is useful when pattern_list begins with the hyphen
delimiter. 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 patterns
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 ALSO


egrep(1), fgrep(1), sed(1), sh(1), attributes(5), environ(5),
largefile(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)