UNIX for Dummies Questions & Answers

Hi UF family members,

I am intermediate in Unix language and scripting.I know the redirection systems in unix,but the below statement confuses me:

#!/bin/ksh
. $HOME/.profile 2>&-

Actually this is an extract from a unix script which was trying to set the environment variables through the script '.profile'.But the error is redirected to somewhere represented as '&-'

Can anyone give a description of what '&-' means?
Your help is appreciated

With Regards
Dileep Pattayath

you are closing the file descriptor.

Can you ellaborate?

I think the line

Code:

. $HOME/.profile 2>&-

closes the error stream. So, If your shell script writes to the error stream or any command produces errors, it doesnt get displayed on to the terminal. For example,

Code:

exec 2>&-
echo "Does this get printed??"
grep junk filename ##filename doesnot exist

gives,

Code:

rkumar@bdc4reteaix1w: /home/rkumar/unix_forum >./teststream
Does this get printed??

if i change the lines to

Code:

exec 1>&-
echo "Does this get printed??"
grep junk filename

then,

Code:

rkumar@bdc4reteaix1w: /home/rkumar/unix_forum >./teststream
grep: 0652-033 Cannot open filename

Doing ". $HOME/.profile 2>&-" is not a great idea. A better approach would be ". $HOME/.profile 2>/dev/null". FD 2 should be open to something so that writes to STDERR succeed. (And the output will still be discarded.) A program might decide to abort if it can't write to STDERR.

Yes,you are right.Thank you so much for such an ellaborate and vivid description.

Thanks for your time and effort

With Regards
Dileep

Yes,I agree with your idea.Thanks for your reply

With Regards
Dileep