How to know last command run successfully : Linux / Unix

In this post I am sharing a small and useful tip about, how to know last command run successfully in Linux and Unix .The post will explain ,to get the exit status of command used last time. As a System Engineer, sometimes I have to check the success status of last command I run on terminal.It is not only with command but you can apply this for script also.

To know the exit status of last command, run below given command

echo $? 

You will get the output in integer.
If output is ZERO ( 0 ), it means command has been run successfully. Whereas if output of the command is NON ZERO then command was not run successfully.

See given below example

linux@tuxworld:/tmp$ ls 
acroread_1002_1002  orbit-linux  plugtmp-2	     pulse-PKdhtXMmr18n  unity_support_test.0
kde-linux	    plugtmp	 plugtmp-3	     ssh-RRoiHGlxeCVF
ksocket-linux	    plugtmp-1	 pulse-EfTYmbAMhCGe  tmpQA7rpT
linux@tuxworld:/tmp$ 
linux@tuxworld:/tmp$ echo $?
0
linux@tuxworld:/tmp$ 
linux@tuxworld:/tmp$ lsla
lsla: command not found
linux@tuxworld:/tmp$ 
linux@tuxworld:/tmp$ echo $?
127
linux@tuxworld:/tmp$ 
linux@tuxworld:/tmp$ 

In above given example, you can see after using ls command,I used echo $? command.Its output is ZERO ,it means command run successfully.

Whereas,on after running false command lsla,the echo $? command output is 127. Which is NON ZERO,hence the command was not run successfully