This topic is about Linux Admin – cut Command.
cut and grep are two of the most useful and common commands for a CentOS Administrator. cut is extremely useful for dealing with delimited files such as Linux configuration files, Linux preference files, and CSV files.
| Switch | Action |
|---|---|
| -b | Select only these bytes |
| -c | Select only these characters |
| -d | Use DELIM instead of TAB for field delimiter |
| -s | Only print delimited lines |
Most times, cut will be used to extract specific rows out of text files. Previously, we have used cut to get a listing of all users from /etc/passwd −
[root@centosLocal centos]# cut -d":" -f1 /etc/passwd root bin daemon adm lp sync shutdown
Above is a digested list of system users from /etc/passwd.
Some Linux utilities and applications actually save the output with the functionality of cut in mind. Following is an example of nmap output.
[root@centosLocal centos]# grep open ./http_scans.txt Host: 10.58.52.67 () Ports: 80/open/tcp//http/// Host: 10.58.52.132 () Ports: 80/open/tcp//http/// Host: 10.58.52.133 () Ports: 80/open/tcp//http/// Host: 10.58.52.56 () Ports: 80/open/tcp//http/// Host: 10.58.52.71 () Ports: 80/open/tcp//http/// Host: 10.58.52.132 () Ports: 80/open/tcp//http///
With cut, we can quickly generate a list of internal systems with port 80 listening for outside requests.
[root@centosLocal centos]# grep open ./http_scans.txt | cut -d" " -f2 > open_http_servers.txt [root@centosLocal centos]# head open_http_servers.txt 10.58.52.17 10.58.52.29 10.58.52.30 10.58.52.36 10.58.52.59 10.58.53.89 10.58.53.100 10.58.54.103 10.58.54.148 10.58.54.152 [root@centosLocal centos]#
Cut can also be used by character count.
[root@centosLocal centos]# cut -c 1,2,3,4,5,6,7,8 lanIP-range.txt 10.58.52 10.58.52 10.58.52 10.58.52 10.58.52 10.58.52 10.58.53 10.58.53 10.58.53 10.58.53 10.58.53 10.58.54 10.58.54 10.58.54 10.58.54 10.58.54 10.58.54 10.58.54 10.58.54 10.58.54 10.58.54 10.58.54 10.58.54 10.58.54 10.58.54 10.58.54 10.58.54 [root@centosLocal centos]#
cut is a command that will be used almost daily by a CentOS Administrator. It is a life saver for parsing text and some binary files.
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