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shellconditional-statementsclearcase

Using shell scripts to remove clearcase view if it exists using one liner if

I want to test if a clearcase view exists and execute the remove command only if it exists. I am trying to do it from a shell script in a Linux 6.x environment. I tried to format my conditions both as one-liner as well as full "if" statement, but don't seem to be able to get it to work. What do I need to do to get both - one-liner and full if syntax - approaches working?

Here is the code, in its latest state

#!/bin/ksh
#
STREAMNAME=app_stream_int
PVOB=domain_pvob
VOB=domain_app

viewdir=/opt/local/software/rational/viewstorage
shareddir=/opt/shared/test
storagedir=${shareddir}/viewstorage
projectdir=${shareddir}/projects

ctdir=/opt/rational/clearcase/bin
viewname=$viewdir/test_$STREAMNAME.vws
viewtag=test_$STREAMNAME

echo "STREAMNAME $STREAMNAME - PVOB $PVOB - VOB $VOB"
echo "Removing View if it exists ... \n"

#  [ $(${ctdir}/cleartool lsview ${viewname}) ] && { ${ctdir}/cleartool rmview ${viewname}; echo "view removed" }

#  [ ${ctdir}/cleartool lsview -long ${viewtag} ] && { ${ctdir}/cleartool rmview ${viewname}; echo "view removed" }

#  ${ctdir}/cleartool lsview -long ${viewtag} | grep "Tag" && { ${ctdir}/cleartool rmview ${viewname}; echo "view removed" }

if [ ${ctdir}/cleartool lsview -long ${viewtag} | grep 'Tag' == "0" ]
then
    echo "view found"
    ${ctdir}/cleartool rmview ${viewname}
fi

I would prefer a one-liner type of solution, but 'if' statement will also work.

Solution

  • Provided the command follows the UNIX-convention of exit codes, the general one-liner looks like:

    command && { success1; success2; } || { failure1; failure2; }

    The list following && specifies what should run when command succeeds (exits with 0), while the list following || specifies what should run when the command fails. In the list, note that all the commands end in a semi-colon, including the last one.

    For your specific case, this looks like it'll work:

    "${ctdir}"/cleartool lsview "${viewname}" && { "${ctdir}"/cleartool rmview "${viewname}" && echo "view removed" || echo "cannot remove view"; }

    Here is an example of this pattern in action, using standard commands:

    $ ls foo && { rm -f foo && echo 'removed' || echo 'not removed'; }
ls: cannot access foo: No such file or directory

$ touch foo
$ ls foo && { rm -f foo && echo 'removed' || echo 'not removed'; }
foo
removed

$ sudo touch /foo
$ sudo chmod 600 /foo
$ ls /foo && { rm -f /foo && echo 'removed' || echo 'not removed'; }
/foo
rm: cannot remove ‘/foo’: Permission denied
not removed