grep command means grep prints the matching lines.

Table of Contents
Syntax
grep [OPTION…] PATTERNS [FILE…]
grep [OPTION…] -e PATTERNS … [FILE…]
grep [OPTION…] -f PATTERN_FILE … [FILE…]
Options
- Option Description
- -b : Display the block number at the beginning of each line.
- -c : Display the number of matched lines.
- -h: Display the matched lines, but do not display the filenames.
- -i : Ignore case sensitivity.
- -l : Display the filenames, but do not display the matched lines.
- -n : Display the matched lines and their line numbers.
- -s : Silent mode.
- -v : Display all lines that do NOT match.
- -w : Match whole word.
In man page the describe it
- grep – print lines that match patterns.
- man grep – More details information about grep command.
grep command in Linux with Examples
$ grep 'devopsroles' /home/huupv/devopsroles.txt
// Search firmware in any case root@DevopsRoles ~]# grep -i -w 'firmware' anaconda-ks.cfg -aic94xx-firmware -alsa-firmware -alsa-tools-firmware -ivtv-firmware -iwl100-firmware -iwl1000-firmware -iwl105-firmware -iwl135-firmware -iwl2000-firmware -iwl2030-firmware -iwl3160-firmware -iwl3945-firmware -iwl4965-firmware -iwl5000-firmware -iwl5150-firmware -iwl6000-firmware -iwl6000g2a-firmware -iwl6000g2b-firmware -iwl6050-firmware -iwl7260-firmware -iwl7265-firmware -linux-firmware //Search match word Linux or UNIX in any case [root@DevopsRoles ~]# grep -i -w '^firmware' anaconda-ks.cfg // Search Alphanumeric Characters [root@DevopsRoles ~]# grep "^[[:alnum:]]" anaconda-ks.cfg // Search Alpha Characters [root@DevopsRoles ~]# grep "^[[:alpha:]]" anaconda-ks.cfg // Search Blank Characters [root@DevopsRoles ~]# grep "^[[:blank:]]" anaconda-ks.cfg // Search Digit Characters [root@DevopsRoles ~]# grep "^[[:digit:]]" anaconda-ks.cfg // Search Lower Letters [root@DevopsRoles ~]# grep "^[[:lower:]]" anaconda-ks.cfg // Search Punctuation Characters [root@DevopsRoles ~]# grep "^[[:punct:]]" anaconda-ks.cfg // Search Uppercase Letters [root@DevopsRoles ~]# grep "^[[:upper:]]" anaconda-ks.cfg
How to match an only dot (.)
[root@DevopsRoles ~]# grep 'conf\.d' anaconda-ks.cfg pushd /etc/dracut.conf.d /etc/dracut.conf.d/vmware-fusion-drivers.conf /etc/dracut.conf.d/hyperv-drivers.conf /etc/dracut.conf.d/nofloppy.conf
Read all files under each directory, recursively
[root@DevopsRoles ~]# grep -R "firmware" /root /root/original-ks.cfg:-aic94xx-firmware /root/original-ks.cfg:-alsa-firmware /root/original-ks.cfg:-alsa-tools-firmware /root/original-ks.cfg:-ivtv-firmware /root/original-ks.cfg:-iwl100-firmware /root/original-ks.cfg:-iwl1000-firmware /root/original-ks.cfg:-iwl105-firmware /root/original-ks.cfg:-iwl135-firmware /root/original-ks.cfg:-iwl2000-firmware /root/original-ks.cfg:-iwl2030-firmware /root/original-ks.cfg:-iwl3160-firmware /root/original-ks.cfg:-iwl3945-firmware /root/original-ks.cfg:-iwl4965-firmware /root/original-ks.cfg:-iwl5000-firmware /root/original-ks.cfg:-iwl5150-firmware /root/original-ks.cfg:-iwl6000-firmware /root/original-ks.cfg:-iwl6000g2a-firmware /root/original-ks.cfg:-iwl6000g2b-firmware /root/original-ks.cfg:-iwl6050-firmware /root/original-ks.cfg:-iwl7260-firmware /root/original-ks.cfg:-iwl7265-firmware /root/original-ks.cfg:-linux-firmware /root/anaconda-ks.cfg:-aic94xx-firmware /root/anaconda-ks.cfg:-alsa-firmware /root/anaconda-ks.cfg:-alsa-tools-firmware /root/anaconda-ks.cfg:-ivtv-firmware /root/anaconda-ks.cfg:-iwl100-firmware /root/anaconda-ks.cfg:-iwl1000-firmware /root/anaconda-ks.cfg:-iwl105-firmware /root/anaconda-ks.cfg:-iwl135-firmware /root/anaconda-ks.cfg:-iwl2000-firmware /root/anaconda-ks.cfg:-iwl2030-firmware /root/anaconda-ks.cfg:-iwl3160-firmware /root/anaconda-ks.cfg:-iwl3945-firmware /root/anaconda-ks.cfg:-iwl4965-firmware /root/anaconda-ks.cfg:-iwl5000-firmware /root/anaconda-ks.cfg:-iwl5150-firmware /root/anaconda-ks.cfg:-iwl6000-firmware /root/anaconda-ks.cfg:-iwl6000g2a-firmware /root/anaconda-ks.cfg:-iwl6000g2b-firmware /root/anaconda-ks.cfg:-iwl6050-firmware /root/anaconda-ks.cfg:-iwl7260-firmware /root/anaconda-ks.cfg:-iwl7265-firmware /root/anaconda-ks.cfg:-linux-firmware
Conclusion
grep command in Linux is the simple command in Linux. It is the most popular in-use terminal Linux print line that matches patterns. Thank you for reading the DevopsRoles page!