Understanding ${parameter}


 
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# 1  
Old 03-26-2009
Understanding ${parameter}

I was reading Bash Cookbook and it had a line of command that assigned a value from var2 to var1 if var1 was empty. Someone told me I could do the same with ${parameter}.

I'm just trying to understand this. Would the following be correct?

For:

Code:
answer=
default=1

Should I assume that the two lines bellow will do the same?

Code:
[ -z "$answer" ] && answer="$default"
# or
${answer:=$default} 2> /dev/null

Thanks,

Vic.
# 2  
Old 03-26-2009
Both commands basically do the same thing.
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