Analyze and store logs
The grep command is used to search text from the file or lines. By default, grep displays the matching lines. It is one of the most useful commands on UNIX and Linux operating systems.
grep 'word' filename grep 'word' file1 file2 grep 'string1 string2' filename command | grep 'something' grep --color 'data' filename
To find log entries:
grep -i - ignores case when searching (example: grep -i oct /var/log/secure) grep -v - displays all but matched lines. Useful when you want to exclude some patterns (example: grep -v Oct /var/log/secure # excludes October from the log file) grep -e - matches regular pattern against the text) (example: grep -e "^$" file # find all the empty lines in the file) grep -c - prints only the number of matched lines
Using grep command