Echo command

The Echo command is also used for checking whether the previous command is executed correctly or not.

root@tester ~]# touch test.txt
[root@tester ~]# echo $?
0
It display zero when it is executed correctly, If the command is not correctly executed it will show some numbers like below.

[root@tester ~]# tuch test1.txt
-bash: tuch: command not found
[root@tester ~]# echo $?
127

Echo command is also used to check the current working shell of the users.

[root@tester ~]# echo $SHELL
/bin/bash

echo *? to know the numbe of arguments passed.

You can also check the version with the below command.

[root@tester ~]# /bin/bash --version
GNU bash, version 3.00.15(1)-release (i686-redhat-linux-gnu)
Copyright (C) 2004 Free Software Foundation, Inc.