Shell Scripting Commands

In shell scripting How to indentify that the previous command was run successfully?

Questions by siddhishah_999

Showing Answers 1 - 9 of 9 Answers


  • May 2nd, 2009

If a command is executed successfully then the exit status of a command is 0. We can test whether a command is execute successfully or not by writing 2 line

[ command_name ]       # command_name is any unix command
echo $?       

 #  $? contains success/failure of the last command that has been executed

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  • Jun 11th, 2009

as per my knowledge, if any person executing any command on unix prompt,definately either it will the output or syntax error.If you are executing any script and you want to check the whether it completed successfully or not.Then execute the script in debugging mode.
                                                           If anybody have a better answer then please forward me on  

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If you want to check that your script has successfully ran. For this you have to do error handling for each command by displaying echo $?

"?" is a inbuilt variable in Shell Scripting, the value for this is assinged by shell after execution of any command to zero(success) or non-zero(failure).

so check this after each command. If somewhere it throws the unexpected values than do error handling there.

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  • Jun 6th, 2010

Use command

echo $?

at prompt.

If the output of command is 0 than succesfully executed.
If the output is non -zero than not successfully executed.

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  • Jun 26th, 2011

in 2 ways it can be done:
1st way
$ echo $?  

2nd way:

$ pwd 2> error| cat error|wc -l
$ cat h 2> error| cat error|wc -l

pwd or cat or any command if outpt is 0 then successful else failed.

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  • Oct 4th, 2017

echo $?
if answer 0 then last command was successful.
if answer is any numeric value then last command is not successful.

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