Linux Admin - wc Command

wc is useful for counting occurrences in a file. It helps print newline, word, ad byte count from each file. Most useful is when combined with grep to show matches for a certain pattern.

We can see our system has 5 users with a group id of 0. Then upon further inspection only the root user has shell access.

[root@centosLocal centos]# cat /etc/passwd | cut -d":" -f4 | grep "^0" |  wc -l 
5 
[root@centosLocal centos]# cat /etc/passwd | cut -d":" -f4,5,6,7 | grep "^0" 
0:root:/root:/bin/bash 
0:sync:/sbin:/bin/sync 
0:shutdown:/sbin:/sbin/shutdown 
0:halt:/sbin:/sbin/halt 
0:operator:/root:/sbin/nologin 
[root@centosLocal centos]#