The egrep command searches the contents of one or more files for a pattern using extended regular expression metacharacters. Extended regular expression metacharacters include the regular expression metacharacters that the grep command uses, plus some additional metacharacters. The table describes the additional metacharacters.
| Metacharacter | Purpose | Sample | Result |
|---|---|---|---|
+ |
Matches one or more of the preceding characters |
'[a-z]+ark' |
Matches one or more lowercase letters followed by ark (for example, airpark, bark, dark, landmark, shark, sparkle, or trademark) |
x|y |
Matches either x or y |
'apple|orange' |
Matches for either expression |
( | ) |
Groups characters |
'(1|2)+' 'search(es|ing)+' |
Matches for one or more occurrences (for example, 1 or 2, searches, or searching) |
The syntax for the egrep command is:
egrep -options pattern filenames
To search for all lines containing one or more lowercase alphabets followed by the pattern ‘body‘ one or more times, perform the command:
$ egrep '[a-z]+body' /etc/passwd nobody:x:60001:60001:NFS Anonymous Access User:/: nobody4:x:65534:65534:SunOS 4.x NFS Anonymous Access User:/:
To search for lines containing the pattern Network Admin or uucp Admin, perform the command:
$ egrep '(Network|uucp) Admin' /etc/passwd uucp:x:5:5:uucp Admin:/usr/lib/uucp: nuucp:x:9:9:uucp Admin:/var/spool/uucppublic:/usr/lib/uucp/uucico listen:x:37:4:Network Admin:/usr/net/nls: