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Instead of writing a multiline if/then/else/fi construct you can do that by one line

Terminal - Instead of writing a multiline if/then/else/fi construct you can do that by one line
[[ test_condition ]] && if_true_do_this || otherwise_do_that
2009-02-20 21:45:21
User: stallmer
24
Instead of writing a multiline if/then/else/fi construct you can do that by one line

instead of writing:

if [[ "$1" == "$2" ]]; then

echo "$1 is equal $2"

else

echo "$1 differs from $2"

fi

do write:

[[ "$1" == "$2" ]] && echo "$1 is equal $2" || echo "$1 differs from $2"

Alternatives

There is 1 alternative - vote for the best!

Terminal - Alternatives
true && { echo success;} || { echo failed; }
2009-04-02 01:49:25
Functions: echo true
23

This will perform one of two blocks of code, depending on the condition of the first. Essentially is a bash terniary operator.

To tell if a machine is up:

ping -c1 machine { echo succes;} || { echo failed; }

Because of the bash { } block operators, you can have multiple commands

ping -c1 machine && { echo success;log-timestamp.sh }|| { echo failed; email-admin.sh; }

Tips:

Remember, the { } operators are treated by bash as a reserved word: as such, they need a space on either side.

If you have a command that can fail at the end of the true block, consider ending said block with 'false' to prevent accidental execution

Know a better way?

If you can do better, submit your command here.

What others think

[[ true ]] && false || echo "Not exactly the same."
Comment by silas 322 weeks ago

you can put an if construct all on one line;

if [[ test_condition ]]; then do_stuff_here; else do_other_stuff_here; fi

one advantage of using the actual if-statement is that you can add things in either clause without needing to use a set of braces. If you wanted to do it with braces, though, you could do:

[[ test_condition ]] && { true_stuff_1; true_stuff_2; } || { false_stuff_1; false_stuff_2; }
Comment by woxidu 321 weeks ago

Your point of view

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