Logical AND
From Linux Shell Scripting Tutorial - A Beginner's handbook
Logical and (&&) is boolean operator. It can execute commands or shell functions based on the exit status of another command.
Contents |
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.
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.
Lookup a username in /etc/passwd file
grep "^vivek" /etc/passwd && echo "Vivek found in /etc/passwd"
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; }
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