Question

I am writing an installation script, and would like it to install in a local directory if the user does not have root access.

specifically, I am looking for the code that goes between the carats (<>)

if [[<do I have root access? = TRUE>]]; then
    .. install .. 
else
    .. install  in $HOME/mylib .. 
fi

Answer 1

For bash, you can use the EUID variable:

if [ "$EUID" == 0 ] ; then
    ..something..
else
    ..something else
fi

For a POSIX-compliant solution, use:

if [ "`id -u`" == 0 ] ; then

Although be aware that the usual answer to your question is “don’t do that”. You never know when someone will decide to run your code in an environment you did not expect… So in general, instead of “check permissions then do something”, a better approach is “try to do something and then detect if it fails”.