tail VS cat VS grep(RedHat Linux)

tail VS cat VS grep(RedHat Linux)

[mrxu@localhost ~]$ groupadd -g 600 testgroup
bash: /usr/sbin/groupadd: Permission denied
[mrxu@localhost ~]$ sudo groupadd -g 600 testgroup
[mrxu@localhost ~]$ tail -1 /etc/group
testgroup:x:600:
[mrxu@localhost ~]$ cat /etc/group|grep stu
[mrxu@localhost ~]$ cat /etc/group|grep testgroup
testgroup:x:600:
[mrxu@localhost ~]$ grep testgroup /etc/group
testgroup:x:600:
[mrxu@localhost ~]$

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