egrep(1) manual page
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egrep - search a file for a pattern using full regular expressions
/usr/bin/egrep [ -bchilnsv ] [ -e pattern_list ] [ -f file ] [
strings ] [ file... ]
/usr/xpg4/bin/egrep [ -bchilnsvx ] [ -e pattern_list
] [ -f file ] [ strings ] [ file... ]
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egrep (expression grep) searches files for a pattern of
characters and prints all lines that contain that pattern. egrep uses full
regular expressions (expressions that have string values that use the full
set of alphanumeric and special characters) to match the patterns. It uses
a fast deterministic algorithm that sometimes needs exponential space.
If
no files are specified, egrep assumes standard input. Normally, each line
found is copied to the standard output. The file name is printed before
each line found if there is more than one input file.
/usr/bin/egrep
accepts full regular expressions as described on the regexp(5)
manual page,
except for \( and \), and with the addition of:
.- A full regular expression
followed by + that matches one or more occurrences of the full regular
expression.
.- A full regular expression followed by ? that matches 0 or 1
occurrences of the full regular expression.
.- Full regular expressions separated
by | or by a NEWLINE
that match strings that are matched by any of the expressions.
.- A full regular expression that may be enclosed in parentheses () for grouping.
Be careful using the characters $, *, [, ^, |, (, ), and \ in full regular
expression, because they are also meaningful to the shell. It is safest
to enclose the entire full regular expression in single quotes fm...fm.
The
order of precedence of operators is [], then *?+, then concatenation, then
| and NEWLINE
.
/usr/xpg4/bin/egrep uses the regular expressions
described in the EXTENDED REGULAR EXPRESSIONS section of the regex(5)
manual page.
The following options are supported:
- -b
- Precede 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
- Print only a count of the
lines that contain the pattern.
- -e pattern_list
- Search for a pattern_list
(full regular expression that begins with a -).
- -f file
- Take the list of full
regular expressions from file.
- -h
- Suppress printing of filenames when searching
multiple files.
- -i
- Ignore upper/lower case distinction during comparisons.
- -l
- Print the names of files with matching lines once, separated by NEWLINE
s.
Does not repeat the names of files when the pattern is found more than
once.
- -n
- Precede each line by its line number in the file (first line is
1).
- -s
- Work silently, that is, display nothing except error messages. This
is useful for checking the error status.
- -v
- Print all lines except those
that contain the pattern.
- -x
- Consider only input lines
that use all characters in the line to match an entire fixed string or
regular expression to be matching lines.
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 will be used.
- pattern
- Specify a pattern to be used during the search for input.
- pattern
- Specify 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.
See
environ(5)
for descriptions of the following environment variables that
affect the execution of egrep: LC_COLLATE
, LC_CTYPE
, LC_MESSAGES
, and NLSPATH
.
The following exit values are returned:
- if any matches are
found
- if no matches are found
- for syntax errors or inaccessible files (even
if matches were found).
fgrep(1)
, grep(1)
, sed(1)
, sh(1)
, environ(5)
,
regex(5)
, regexp(5)
Ideally there should be only one grep command,
but there is not a single algorithm that spans a wide enough range of space-time
tradeoffs. Lines are limited to BUFSIZ
characters; longer lines are truncated.
BUFSIZ
is defined in <stdio.h>.
/usr/xpg4/bin/egrep
is identical to /usr/xpg4/bin/grep -E (see grep(1)
). Portable applications
should use /usr/xpg4/bin/grep -E.
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