UNIX for Advanced & Expert Users

ahhhhh..... i got you era. it simplified the whole thing.. i wasn't aware of -p option.. now i can cut short my script at many places.

is the following way is the right to check a file in a folder and if file not in the folder copy from the repositry.
cd /var/lib
ls -l libstdc++.so.5 >>/dev/null
if [ $? -ne 0 ]
then
cp repository path
echo "new file copied......"
fi

Not really, no. Using ls and redirecting to /dev/null is not particularly elegant (and using the -l option to then just throw away the results is rather wasteful).

Code:

test -e /var/lib/libstdc++.so.5 || cp -v repository path

The || is a shorthand for "or else". The following is closer to what you have:

Code:

if ! [ -e /var/lib/libstdc++.so.5 ]
then
  cp repository path
  echo "new file copied" >&2
fi

Note that test and [ are really basically the same command.

thank you so much era,. surely u gonna take me one step ahead from a beginer.

if i run a command, suppose # ./createreg -new /opt/server1
now if i have to test in script wather it executed sucsessfully, Like
./createreg -new /opt/server1
if true
do next step
else
exit the script
fi

now in my script i am doing like this
./createreg -new /opt/server1
if [ $? != 0 ] ; then echo "Instalation Error ........... Exit 127 " ; exit 1
else
proceed
fi

Please guide if it is a right way to do it

Use -ne for an integer comparison:

Code:

if [ $? -ne 0 ]

Regards