John Redyns John Redyns - 2 months ago 7
Bash Question

Shell - Multiple commands in one line

Say I have a file

/templates/apple
and I want to


  1. put it in two different places and then

  2. remove the original.



So,
/templates/apple
will be copied to
/templates/used
AND
/templates/inuse

and then after that I’d like to remove the original.

Is
cp
the best way to do this, followed by
rm
? Or is there a better way?

I want to do it all in one line so I’m thinking it would look something like:

cp /templates/apple /templates/used | cp /templates/apple /templates/inuse | rm /templates/apple


Is this the correct syntax?

Answer

You are using | (pipe) to direct the output of a command into another command. What you are looking for is && operator to execute the next command only if the previous one succeeded:

cp /templates/apple /templates/used && cp /templates/apple /templates/inuse && rm /templates/apple

Or

cp /templates/apple /templates/used && mv /templates/apple /templates/inuse

To summarize (non-exhaustively) bash's command operators/separators:

  • | pipes (pipelines) the standard output (stdout) of one command into the standard input of another one. Note that stderr still goes into its default destination, whatever that happen to be.
  • |&pipes both stdout and stderr of one command into the standard input of another one. Very useful, available in bash version 4 and above.
  • && executes the right-hand command of && only if the previous one succeeded.
  • || executes the right-hand command of || only it the previous one failed.
  • ; executes the right-hand command of ; always regardless whether the previous command succeeded or failed. Unless set -e was previously invoked, which causes bash to fail on an error.
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