Terminal or not Terminal

[Marty Metras]

Some where I saw a command/script the would tell if a script was runing on a terminal or as a process.
I have a couple scripts that can be run online or as a batch There are some interactive things that should be entered when interactive and default when batched. I know there is a command that will tell me this but I can not remember what it is.

something like
if [ "$THIS_IS_A_TERMINAL" = "YES" ]
then
echo "do something"
else
echo "let the computer do something else"
fi

Can you help?
Marty

[Mark Grant]

how about

RESULT=`tty`
if [ $RESULT = 0 ]
then
echo "do something"
else
do something that isn't an echo becuase we haven't go a terminal to write to :)
fi

[Massimo Bianchi]

if tty -s
then
echo "INTERACTIVE SESSION"
fi

Massimo

[Mark Grant]

Ok Massimo, you win this round :)

[Elmar P. Kolkman]

tty is the way to go, but redirect stderr to the same output. tty will give you the device it is running on.

RESULT=`tty 2>&1 | grep '^/dev/'`
if [ -n "$RESULT" ]
then
# You have a terminal
else
# No terminal, run unattended
fi

You could also remove the RESULT var:
if tty 2>&1 | grep -q '^/dev/'
then
# Run attended
else
# Run unattended
fi

[A. Clay Stephenson · Accepted solution]

It's even easier:

if [[ -t 0 && -t 1 && -t 2 ]]
then
echo "Stdin (0), Stdout (1), and Stderr (2) are tty devices"
fi

Generally, the test is only done for stdin.

[Marty Metras]

I'm not sure on this one.

if [[ -t 0 && -t 1 && -t 2 ]]
then
echo "Stdin (0), Stdout (1), and Stderr (2) are tty devices"
fi

Isn't Stdin (0), Stdout (1), and Stderr (2)always available?
It works!
Marty

[Mark Grant]

Marty,

Give up and give A.Clay the bunny :)

Anything with the standard input closed, is, by definition, not realy attached to a terminal and therefore the test is perfectly valid and smarter than the other suggestions (especially mine).

[Massimo Bianchi]

Just for info: "tty -s"

The -s option
inhibits printing of the terminal path name and any diagnostics,
providing a means to test only the exit code.



NO POINTS PLEASE.

Massimo

[Marty Metras]

Done deal.
I already have the scrapt installed in many places. Tested and works great.
I like the simple things.

Thank you and happy holidays.
Marty