Shell Programming and Scripting

Hi,

I am writing an error logging script where upon error, the erroneous line

Code:

$LINENO

and erroneous command are captured

Code:

$BASH_COMMAND

Code:

trap 'echo $LINENO $BASH_COMMAND' ERR

But I don't know how to suppress logging error on some code where I redirect the error to /dev/null/ as below -

Sample code -

Code:

 
 files_available=`ls ${dir}/${file_name} 2> /dev/null`

The trap is logging error line no. and the command for the above line when the files are not available. Is there a way to suppress the logging of the redirected errors?

-P

Reset the trap, and set afterwards again?

Replace the ls by echo, and set the shell option nullglob before the command (and unset it afterwards, unless you want to keep this setting).

In general, I agree with RudiC.

In the case above you are not actually using wildcards so ls should be producing one or zero files. Why not this instead?

Code:

if [ -f "${dir}/${file_name}" ]
then  files_available="${dir}/${file_name}"
else files_available=
fi

If a wildcard is involved (perhaps in your script filename is set to, say, *.c), you could try this:

Code:

shopt -s nullglob
files_available=`printf "%s\n" "${dir}/${file_name}" 2> /dev/null`

Note that this is a bashism that came from zsh so you would have to check if it works with your shell.

Andrew

You are right, Andrew! I don't know why I believed this would be a wildcard expression! I must have been out of my mind!

Thank you for pointing this out...