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up vote 2 down vote favorite

Why variable $c in end of code not echo "smile" but only echo empty value?

I wont get variable $c after end of "if operator" but when operator finish job my value $c not return "smile" but only return "" (empty value)

#!/bin/bash
###
## sh example.sh

a="aaa"
b="bbb"

if [ "$a" != "$b" ]; then ( 
c="smile"
echo "echo inside if:"
echo $c # in this echo "smile" 
) else ( 
c="yes" 
) fi

echo "echo after fi:"
echo $c  # echo ""  # why this not echo "smile"

result:

[root@my-fttb ~]# sh /folder/example.sh
echo inside if:
smile
echo after fi:

[root@my-fttb ~]#
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2 Answers 2

up vote 6 down vote accepted

Get rid of the parentheses. Parentheses create sub-shells, and variables set in a sub-shell aren't propagated back to the parent shell.

if [ "$a" != "$b" ]; then
    c="smile"
    echo "echo inside if:"
    echo $c  # in this echo "smile" 
else
    c="yes" 
fi
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up vote 4 down vote

The parenthesis if the if statement, creates a sub-shell, so the variables are not changed in the parent shell.

Remove the parenthesis:

if [ "$a" != "$b" ]; then
    c="smile";
    echo "echo inside if:"
    echo $c; # in this echo "smile" 
else
c="yes"; 
fi
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