I'm trying to set up a shell script that will start a screen
session (or rejoin an existing one) only if it is invoked from an interactive shell. The solution I have seen is to check if $-
contains the letter "i":
#!/bin/sh -e
echo "Testing interactivity..."
echo 'Current value of $- = '"$-"
if [ `echo \$- | grep -qs i` ]; then
echo interactive;
else
echo noninteractive;
fi
However, this fails, because the script is run by a new noninteractive shell, invoked as a result of the #!/bin/sh
at the top. If I source the script instead of running it, it works as desired, but that's an ugly hack. I'd rather have it work when I run it.
So how can I test for interactivity within a script?