What's the equivalent to && when writing a bash script?

Question

I apologize in advance if this is a duplicate question. I did make an effort to search/check before asking here.

I'm comfortable with writing one-liners like this:

foocommand && foocommand2 && foocommand3

The idea being that I only want subsequent commands to run if the previous one was "successful".

I'm writing a somewhat lengthy script and this one-liner isn't feasible because it looks like a huge block of confusing code to everyone else.

I want to space out the commands and write comments inbetween them in the script. How can I do this and still have the equivalent of && in there?

Answer 1

You can change the shebang line to

#!/bin/bash -e

After any error, the script will stop.

Answer 2

You can do it like this:

#!/bin/sh
ls -lh &&
    # This is a comment
    echo 'Wicked, it works!'

I hope I understood what you asked correctly.

Answer 3

If you don't like the set -e idea, maybe you can invert the logic.

foocommand || exit 1
foocommand2 || exit 2
foocommand3 || exit 3

More usefully, replace exit with something to print a useful error message, then exit. Inside a function, of course, you want return instead of exit.

Answer 4

You can use if else fi blocks instead.

if foocommand; then

  # some comments

  if foocommand2; then

    # more comments

    foocommand3
  fi
fi

It's a little more readable.

Alternatively you can just use \ to break your big 1 liner into several lines

foocommand && \
  # some comment
  foocommand2 && \
    # more comment
    foocommand3

But of course this can be confusing to the untrained eye.

Answer 5

You could consider using nested if statements. Other option is to use curly's to group like { true && echo hi; } || echo huh

Update 1:

Here's an example without newlines/comments:

{ { false && echo "inner true"; } && { echo "inner true" && true; } || { echo "inner false" && false; } || echo "outter false"; }

Answer 6

Split each sequence of commands into functions:

big_block_1() {
  # ...
}
big_block_2() {
  # ...
}
big_block_3() {
  # ...
}

big_block_1 && big_block_2 && big_block_3

Answer 7

I always like to write a "fail" function which lets me specify the thing I was going to do when the failure occurred and then use the || pattern. Like the following:

function fail() {
  echo "Failure: ${@}"
  exit 1
}

foocommand || fail "couldn't foo"