Shell Scripting

How not to show messages?

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Join Date: Aug 2009

Posts: 17

Reputation: darangho is an unknown quantity at this point

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darangho

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Newbie Poster

How not to show messages?

Aug 25th, 2009

Hi all
I just have questions about
how not to show messages after you execute a certain command.

for example whenever you execute "which xxx"
there will always be a message on the terminal
saying its path or command not found will be written.

is that possible to write a shell script file
without showing these kind of messages?

Thanks!

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Join Date: Feb 2009

Posts: 3,327

Reputation: sknake has much to be proud of

Solved Threads: 599

sknake

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.NET Enthusiast

Re: How not to show messages?

Aug 25th, 2009

Send stdout and stderr to /dev/null:

 Help with Code Tags 
 bash Syntax (Toggle Plain Text) 
sk@sk:~$ which bash
/bin/bash
sk@sk:~$ which bash >> /dev/null 2>&1
sk@sk:~$
sk@sk:~$ which bash
/bin/bash
sk@sk:~$ which bash >> /dev/null 2>&1
sk@sk:~$

You can still access the return value which is usually why this is done. Here is an example:

 Help with Code Tags 
 bash Syntax (Toggle Plain Text) 
sk@sk:~$ which bash >> /dev/null 2>&1
sk@sk:~$ echo $?
0
sk@sk:~$ which asoija0cjas9cuasc >> /dev/null 2>&1
sk@sk:~$ echo $?
1
sk@sk:~$ which bash >> /dev/null 2>&1
sk@sk:~$ echo $?
0
sk@sk:~$ which asoija0cjas9cuasc >> /dev/null 2>&1
sk@sk:~$ echo $?
1

Scott Knake
Custom Software Development
Apex Software, Inc.

•

Join Date: Aug 2009

Posts: 17

Reputation: darangho is an unknown quantity at this point

Solved Threads: 0

darangho

Offline

Newbie Poster

Re: How not to show messages?

Aug 25th, 2009

Thank you very much
problem solved!

•

Originally Posted by sknake

Send stdout and stderr to /dev/null:
Help with Code Tags

bash Syntax (Toggle Plain Text)
sk@sk:~$ which bash
/bin/bash
sk@sk:~$ which bash >> /dev/null 2>&1
sk@sk:~$
sk@sk:~$ which bash /bin/bash sk@sk:~$ which bash >> /dev/null 2>&1 sk@sk:~$
You can still access the return value which is usually why this is done. Here is an example:
Help with Code Tags

bash Syntax (Toggle Plain Text)
sk@sk:~$ which bash >> /dev/null 2>&1
sk@sk:~$ echo $?
0
sk@sk:~$ which asoija0cjas9cuasc >> /dev/null 2>&1
sk@sk:~$ echo $?
1
sk@sk:~$ which bash >> /dev/null 2>&1 sk@sk:~$ echo $? 0 sk@sk:~$ which asoija0cjas9cuasc >> /dev/null 2>&1 sk@sk:~$ echo $? 1