CODEWITHSUNDEEP
bash
dagda1
dagda1

Reputation: 28860

assign bash variable using a ternary like syntax

I have the following bash code:

if [ $NOD_ENV = "production" ]; then IS_PRODUCTION=1; else IS_PRODUCTION=0; fi
if [ $IS_PRODUCTION ]; then VALUE="$VALUE_PRODUCTION"; else CDN_HEADER_VALUE="$PRODUCTION"; fi
# etc
fi

I am getting some unexpected output assigning variables this way. How could I do this better?

Upvotes: 0

Views: 88

Answers (2)

KamilCuk
KamilCuk

Reputation: 141483

It's a cool trick to set boolean variable in bash to the string "true" or "false":

if [ $NOD_ENV = "production" ]; then IS_PRODUCTION=true; else IS_PRODUCTION=false; fi
if "$IS_PRODUCTION"; then VALUE="$VALUE_PRODUCTION"; else CDN_HEADER_VALUE="$PRODUCTION"; fi;

What happens here, is that IS_PRODUCTION has the string "true" or "false". Once you run if "$IS_PRODUCTION" the variable is expanded which results in if true or if false. true and false are builtin commands, which get run, and return - zero status for true and non-zero status for false.

Upvotes: 1

Forrest
Forrest

Reputation: 236

You need to explicitly test the value of $IS_PRODUCTION: 

if [ $IS_PRODUCTION = 0 ]; then  ...

if [ $IS_PRODUCTION ] only tests whether the length of $IS_PRODUCTION is non-zero.

As a side note, [ is actually a program, and you can see the options for it by running /usr/bin/[ --help (the /usr/bin seems important on my system for some reason ...)

Upvotes: 2

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