I am executing a program wp1s0000.sh_old and it is executing as expected irrespective of the extension "sh_old"
how is this possible ??
In Unix, the extension or filename does not determine whether the file is executable or not. Type
file wp1s0000.sh_old
to know the actual type of the file. Note that name may be misleading in some cases.
Also, check for access permissions and particularly the x (execute) permission. Use chmod command to change access permissions of a file.