if statement help

Shell Programming and Scripting
1

Hi Gurus,

New to Unix... What does the following if commands do?

if [ ! "$ORACLE_HOME" ]
then
. ${HOME}/.profile
fi

if [ ! "$COMMON_SOURCED" ]
then
. ./.common
fi

Also please give me some tutorials for Unix which I can start with. Also please gimmme examples for shell scripting.

Thanks and Regards,

2

If the variable is empty or unset, then execute the code.

The more usual way to do it is:

if [ -z "$ORACLE_HOME" ]
then
. ${HOME}/.profile
fi

Here are some links to shell resources.

3

johnson,

Thanks a lot for the needful.

what does the . ${HOME}/.profile and . ./.common do?

Thanks and Regards,

4

They source the files ${HOME}/.profile and ./.common.

That means that they are executed in the current shell and can therefore affect the environment (e.g., set variables) of that shell.