program exit return 0 or 1?

blackzone · 07-20-2006, 04:37 AM

Under linux if a program exit successfully what does it return?

and when it exit with error what is returned.

Also how do you check under bash shell if the previously runned program exit with error or success?

prozac · 07-20-2006, 04:38 AM

0 for success
non 0 for others.

prozac · 07-20-2006, 04:39 AM

if [ "$?" == "0" ]; then
echo "success!"
else
echo "failed!"
fi

bigearsbilly · 07-20-2006, 04:46 AM

as well as prozac's answer,

Code:

if command; then
    echo success
else
    echo doh
fi

or

Code:

command && echo "yes" || echo "no"

konsolebox · 07-20-2006, 05:00 AM

there are more other ways

the most common and cleanest way is

Code:

if program; then
    echo 0/true
else
    echo 1/false
fi

you can also do this

Code:

program && echo true
program && {
   more statements if true
}

and also include the false parts like

Code:

program && echo true || echo false
program && {
   more statements if true
} || {
   more statements if false
}

but i don't recommend the last ones since sometimes the false parts are executed when the true statements return a false value

you must also note that your program should return true and false values. some programs only return true unless they are interrupted or are caught by a signal

if a program exits or is suspended because of a signal, the return value is always 128 + signal number

you can do exit codes in a bash script using exit /b # by the way