bash, how to use OR || operator in If statement?

Question

Can anybody tell me what is wrong with this syntax:

if [ "$1" == "postfix" || "$1" == "all" ]; then
    echo test
fi

[ a == b ] || [ c == d ] or [ a == b -o c == d ]. Or [[ ... ]] instead. — Kevin
– Kevin, Commented Dec 3, 2014 at 23:56

Alfe · Accepted Answer · 2014-12-03 23:56:45Z

2

Use either

if [ "$1" = "postfix" ] || [ "$1" = "all" ]; then

or

if [ "$1" = "postfix" -o "$1" = "all" ]; then

|| combines two commands (and the [ is a command). Within the [ ... ] the operator -o is used for or.

Another way to use || is to use it inside [[ instead of [.

In any way, the correct operator for equality is = inside [ ... ] as it is the POSIX standard (according to man bash). == is supported, though.

answered Dec 3, 2014 at 23:56

Alfe

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Comments

Gilles Quénot · Accepted Answer · 2014-12-03 23:56:17Z

1

If you want to do this, use [[ test form :

if [[ $1 == "postfix" || $1 == "all" ]; then

[[ is a bash keyword similar to (but more powerful than) the [ command. See http://mywiki.wooledge.org/BashFAQ/031 and http://mywiki.wooledge.org/BashGuide/TestsAndConditionals Unless you're writing for POSIX sh, we recommend [[

or

if [ "$1" == "postfix" ] || [ "$1" == "all" ]; then

answered Dec 3, 2014 at 23:56

Gilles Quénot

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1 Comment

Alfe Over a year ago

There's not much difference to my answer, so ⁺¹ from me ;-)

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