How to tell if user selected "Run In Terminal"

When you double-click a bash script, Ubuntu asks if the user wants to Display, Run, or Run In Terminal...

Is there a way within the script to determine if the user ch开发者_如何学Pythonose "Run In Terminal"?

Strictly speaking, you can't tell whether the user chose "Run In Terminal" after clicking on the script, or fired up a terminal and ran the script from there. But the commands below should help you, especially [ -t 2 ].

if [ -t 1 ]; then
  echo "Standard output is a terminal."
  echo "This means a terminal is available, and the user did not redirect the script's output."
fi

if [ -t 2 ]; then
  echo "Standard error is a terminal." >&2
  echo "If you're going to display things for the user's attention, standard error is normally the way to go." >&2
fi

if tty >/dev/null; then
  echo "Standard input is a terminal." >$(tty)
  echo "The tty command returns the name of the terminal device." >$(tty)
fi

echo "This message is going to the terminal if there is one." >/dev/tty
echo "/dev/tty is a sort of alias for the active terminal." >/dev/tty
if [ $? -ne 0 ]; then
  : # Well, there wasn't one.
fi

if [ -n "$DISPLAY" ]; then
  xmessage "A GUI is available."
fi

Here is an example:

#!/bin/bash

GRAND_PARENT_PID=$(ps -ef | awk '{ print $2 " " $3 " " $8 }' | \
    grep -P "^$PPID " | awk '{ print $2 }')

GRAND_PARENT_NAME=$(ps -ef | awk '{ print $2 " " $3 " " $8 }' \
    | grep -P "^$GRAND_PARENT_PID " | awk '{ print $3 }')

case "$GRAND_PARENT_NAME" in
gnome-terminal)
    echo "I was invoked by gnome-terminal"
    ;;
xterm)
    echo "I was invoked by xterm"
    ;;
*)
    echo "I was invoked by someone else"
esac

Now, let me explain this in a little more details. In the case when script is executed by (in) a terminal, its parent process is always a shell itself. This is because terminal emulators run shell to invoke scripts. So the idea is to look at a grandparent process. If grandparent process is a terminal then you can assume that your script was invoked from a terminal. Otherwise, it was invoked by something else, for example, Nautilus, which is Ubuntu's default file browser.

The following command gives you a parent process ID.

ps -ef | awk '{ print $2 " " $3 " " $8 }' | grep -P "^$PPID " | awk '{ print $2 }'

And this command is giving you a name of your parent's parent process.

ps -ef | awk '{ print $2 " " $3 " " $8 }' | grep -P "^$GRAND_PARENT_PID " | awk '{ print $3 }'

And the final switch statement just compares grandparent process name with some known terminal emulators.

Never tried it, but probably this works:

if [ -t 1 ] ;

Although it would also be false if the output it piped...