| ^ (Caret) | = | match expression at the start of a line, as in ^A. |
| $ (Question) | = | match expression at the end of a line, as in A$. |
| \ (Back Slash) | = | turn off the special meaning of the next character, as in \^. |
| [ ] (Brackets) | = | match any one of the enclosed characters, as in [aeiou]. Use Hyphen "-" for a range, as in [0-9]. |
| [^ ] | = | match any one character except those enclosed in [ ], as in [^0-9]. |
| . (Period) | = | match a single character of any value, except end of line. |
| * (Asterisk) | = | match zero or more of the preceding character or expression. |
| \{x,y\} | = | match x to y occurrences of the preceding. |
| \{x\} | = | match exactly x occurrences of the preceding. |
| \{x,\} | = | match x or more occurrences of the preceding. |
| grep smug files | {search files for lines with 'smug'} |
| grep '^smug' files | {'smug' at the start of a line} |
| grep 'smug$' files | {'smug' at the end of a line} |
| grep '^smug$' files | {lines containing only 'smug'} |
| grep '\^s' files | {lines starting with '^s', "\" escapes the ^} |
| grep '[Ss]mug' files | {search for 'Smug' or 'smug'} |
| grep 'B[oO][bB]' files | {search for BOB, Bob, BOb or BoB } |
| grep '^$' files | {search for blank lines} |
| grep '[0-9][0-9]' file | {search for pairs of numeric digits} |
| grep '^From: ' /usr/mail/$USER | {list your mail} |
| grep '[a-zA-Z]' | {any line with at least one letter} |
| grep '[^a-zA-Z0-9] | {anything not a letter or number} |
| grep '[0-9]\{3\}-[0-9]\{4\}' | {999-9999, like phone numbers} |
| grep '^.$' | {lines with exactly one character} |
| grep '"smug"' | {'smug' within double quotes} |
| grep '"*smug"*' | {'smug', with or without quotes} |
| grep '^\.' | {any line that starts with a Period "."} |
| grep '^\.[a-z][a-z]' | {line start with "." and 2 lc letters} |
grep "unix" *.htm
search all .htm files in the current directory for any reference of unix and give results similar to the below example text.
Search /etc/passwd for boo user:
$ grep boo /etc/passwd
force grep to ignore word case i.e match boo, Boo, BOO and all other combination with -i option:
$ grep -i "boo" /etc/passwd
search recursively i.e. read all files under each directory for a string "192.168.1.5"
$ grep -r "192.168.1.5" /etc/
select only those lines containing matches that form whole words i.e. match only boo word:
$ grep -w "boo" /path/to/file
the number of times that the pattern has been matched for each file using -c (count) option:
$ grep -c 'word' /path/to/file
use -n option, which causes grep to precede each line of output with the number of the line in the text file from which it was obtained:
$ grep -n 'word' /path/to/file
matches only those lines that do not contain the given word. For example print all line that do not contain the word bar:
$ grep -v bar /path/to/file
print name of hard disk devices:
# dmesg | egrep '(s|h)d[a-z]'
Display cpu model name:
# cat /proc/cpuinfo | grep -i 'Model'
the -l option to list file name whose contents mention main():
$ grep -l 'main' *.c
force grep to display output in colors:
$ grep --color vivek /etc/passwd
prints all lines in the file that begin with the letter
a, followed by any one character, then the letters
ple.
grep ^a.ple fruitlist.txt
grep for both "FS" and "HR" at the same time, but return lines that contain either entry.
egrep 'HR|FS' myfile
print all lines containing strings
"abc" or
"def" or both:
grep -E 'abc|def'
print all lines matching exactly
"abc" or
"def" :
grep -E '^abc$|^def$'
