EGREP(1) INTERACTIVE UNIX System EGREP(1)
NAME
egrep - search a file for a pattern using full regular
expressions
SYNOPSIS
egrep [options] full regular expression [file ...]
DESCRIPTION
The egrep command (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.
The egrep command accepts full regular expressions as in
ed(1), except for \( and \), with the addition of:
1. A full regular expression followed by + that matches
one or more occurrences of the full regular expres-
sion.
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 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 regu-
lar expression in single quotes '...'.
The order of precedence of operators is [], then *?+, then
concatenation, then | and new-line.
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.
Command line options are:
-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 pat-
tern.
-i Ignore upper/lower case distinction during comparis-
ons.
-l Print the names of files with matching lines once,
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EGREP(1) INTERACTIVE UNIX System EGREP(1)
separated by new-lines. 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).
-v Print all lines except those that contain the pattern.
-e special_expression
Search for a special expression (full regular expres-
sion that begins with a -).
-f file
Take the list of full regular expressions from file.
-h Prevents the name of the file containing the matching
lines from being appended to that line. Used when
searching multiple files.
SEE ALSO
ed(1), fgrep(1), grep(1), sed(1), sh(1).
DIAGNOSTICS
Exit status is 0 if any matches are found, 1 if none, 2 for
syntax errors or inaccessible files (even if matches were
found).
BUGS
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 charac-
ters; longer lines are truncated. BUFSIZ is defined in
/usr/include/stdio.h, which is included as part of the basic
software development set.
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