grep command in Linux with Examples

grep command means grep prints the matching lines.

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!