Logical AND
From Linux Shell Scripting Tutorial - A Beginner's handbook
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Logical and (&&) is boolean operator. It can execute commands or shell functions based on the exit status of another command.
Contents |
[edit] Syntax
command1 && command2
OR
First_command && Second_command
command2 is executed if, and only if, command1 returns an exit status of zero (true). In other words, run command1 and if it is successfull, then run command2.
[edit] Example
Type the following at a shell prompt:
rm /tmp/filename && echo "File deleted."
The echo command will only run if the rm command exits successfully with a status of zero. If file is deleted successfully the rm command set the exit stats to zero and echo command get executed.
[edit] Lookup a username in /etc/passwd file
grep "^vivek" /etc/passwd && echo "Vivek found in /etc/passwd"
[edit] Exit if a directory /tmp/foo does not exist
test ! -d /tmp/foo && { read -p "Directory /tmp/foo not found. Hit [Enter] to exit..." enter; exit 1; }
[edit] External links
| ← Conditional execution | Home | Logical OR → |
