Bash: If statement with dash o

veryangryman

Hi, can anyone deduce what the if statement means below, specifically the "ash o" parts. That argument doesnt exist in the man page for "test" or "if".

check_params()
{
if [ ! "${PATH}" -o ! "${ACTION_TYPE}" -o ! "${LU_PATH}" ]; then
    usage_msg
    exit 1
fi
}

BrokenArrows

its an argument to whatever executable is being executed.
The ! takes the last argument from the console history and puts it in there.

So what it does really depends on what is being executed in the history.

Skrynesaver

$ if [ 1 -eq 1 -o 2 -gt 3 ] ; then echo OK;fi
OK

$ if [ 1 -eq 0 -o 2 -gt 3 ] ; then echo OK;fi

$ if [ 1 -eq 0 -o 2 -gt 1 ] ; then echo OK;fi
OK

It's the equivalent of an OR

Singer

Skrynesaver wrote: »

$ if [ 1 -eq 1 -o 2 -gt 3 ] ; then echo OK;fi
OK

$ if [ 1 -eq 0 -o 2 -gt 3 ] ; then echo OK;fi

$ if [ 1 -eq 0 -o 2 -gt 1 ] ; then echo OK;fi
OK

It's the equivalent of an OR

Yep. The Advanced Bash Scripting Guide has been my go-to guide for this stuff for... too many years:

http://tldp.org/LDP/abs/html/comparison-ops.html

veryangryman

Thanks guys. Very helpful