I know that this is probably a relatively pointless question, but I am curious as to why exec false closes the terminal just like exit does.
I would also like to know if this is a acceptable way to close the terminal or not.
- Also relevant reading: What's the difference between eval and exec?Sergiy Kolodyazhnyy– Sergiy Kolodyazhnyy2018-07-02 06:32:12 +00:00Commented Jul 2, 2018 at 6:32
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1 Answer
exec false is replacing the current shell by the execution of the command false (here not the shell builtin but /bin/false or whatever false executable that comes first in the PATH) which quickly exits. If the shell was the topmost process running in your terminal emulator, there are no more processes running inside it so the terminal emulator is closed.
This is a an acceptable alternate way to close a terminal, just like would be many similar commands:
exec true exec sleep 0 exec echo ... See also: what-does-an-exec-command-do
- As a side note,
bashwill perform certain cleanup before invokingexecincluding writing commands to.bash_history. So if one simply wants to save to.bash_historyand launch a new shell in the same terminal window, one can do so by typingexec bash.kasperd– kasperd2015-03-12 07:53:56 +00:00Commented Mar 12, 2015 at 7:53 - @jiliagre
execcalls commands found inPATH, not built-ins. For instance,exec [[ $USER = root ]]will returnbash: exec: [[: not founderror. In OP's case,falsethat is called is/bin/false, and not the shell built-in. Otherwise, good answer, hence +1. As a side note,execcan be sort of a cut-off command, i.e. if those three commands in your example were made into a script, nothing beyond firstexecwould be reached, becauseexecwould replace shell called by script with whatever command is on the right ofexec.Sergiy Kolodyazhnyy– Sergiy Kolodyazhnyy2018-07-02 06:31:13 +00:00Commented Jul 2, 2018 at 6:31