title: Bash grep
Bash command: grep
grep command is used to find matching text in input file(s). Default output lists lines from the input file(s) which contain a match to the provided pattern. Options may be used to alter matching behavior or to provide a different output scheme.
grep [options] [pattern] [file_names]
-i, Ignore case when mathing the provided pattern
-v, Show results which do not match the provided pattern.
-l, Instead of outputting matching lines, output the file paths which contain matching text.
-r, Search all files in the provided directories. Directory name(s) or path(s) is used in place of the file name(s) (Search defaults to the current working directory if none is provided)
-c, Output a count of the matching lines.
-E, Use extended regular expressions to define the pattern to be matched. The command alias
egrepis the same as
Search a server log file for lines containing the text “ERROR”:
grep ERROR server.log
Using a pipe to combine commands, list files and folders in the current working directory that contain the text “code”:
ls | grep code
Search for IP 127.0.0.1 in the /etc/hosts file
grep "127.0.0.1" /etc/hosts
Search for oom (out of memory) in /var/log/messages
grep -i oom /var/log/messages
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