Shell Programming and Scripting

what's the difference between this:

Code:

result=`Your_function`

and this

Code:

result = `Your_function`

???

Thanks lot it worked fine.
my requirement is returncode !=0
then list the all files in a directory.

But the files are not listing
Help me.Im new to unix

Returncode = `cd $Path;ls -lrt *$fdate 2>/dev/null | wc -l`
if [ "$Returncode" = 0 ]
then
echo '.......'
else
`cd $Path;ls -lrt *$fdate 2>/dev/null`

Im trying to execute the above code but its not Displaying the files.

Buddy,

You can also use "$?" inorder to check the status code for the last executed command.

Pl dont direct the result to some dummy terminal(/dev/null). We generally do this when we dont need the output and even we dont want that output to be displayed on the screen. Please use the below code:

Returncode = `cd $Path;ls -lrt *$fdate 2>/dev/null | wc -l`
if [ "$Returncode" = 0 ]
then
echo '.......'
else

cd $Path;ls -lrt *$fdate

Now it should display the list of files.

I beleive to discard the error codes alone 2>/dev/null
but even output will display

Vicky Narayan: in this case, $? will be the result code from wc -l, not from ls! But the idea to capture the result with backticks and not echo anything if it's zero is workable.

You still need to remove the spaces around the equals sign, it's a syntax error to leave them out.

However, if you really do need to distinguish between "error" and "no output" (wc -l will be zero in both cases). you will need to decompose it somehow. Maybe something like this:

Code:

postprocess="wc -l"
if ! ls *$frdate >/dev/null; then
  postprocess=false
fi | $postprocess

If you need to do something more if ls fails, just add stuff to the "then" clause. You can also add an "else" clause to only do things when ls is successful. But notice that output from the whole if construction gets piped to wc -l or false (hope that works for you; not sure how portable that is, but this is a proof of concept anyway; change it to "cat >/dev/null" or something if you can't make it work with false.)

Wait a minute. So you don't really care about wc -l at all?

ls files 2>/dev/null will list the files if they are there, and not display a warning if they are not, and set a non-zero exit code if it failed. If that's all you want then there you are.