Bash isn't strictly needed, plain Bourne shell works, using parameter
substitution
man sh | grep -A 2 -i "parameter:-"
${parameter:-word}
Use Default Values. If parameter is unset or null, the expansion of
word is substituted. Otherwise, the value of parameter is substituted.
So:
p=/foobar
read -p "gimme a dir or accept default ($p): " x
x=${x:-$p}
echo $x
...if the user hits <Enter> it shows:
gimme a dir or accept default (/foobar):
/foobar
It's better to put that in a function:
input_dir() { p="${1:-/foobar}" ; read -p "gimme a dir or accept
default ($p): " x ; x=${x:-$p} ; echo $x ; }
This function can even take a parameter, if the default
dir needs to be changed on the fly:
% input_dir
gimme a dir or accept default (/foobar): /foobar2
/foobar2
# store results of routine in $x
% x=`input_dir /tmp`
gimme a dir or accept default (/tmp):
% echo $x
/tmp
(Debian's minimal 'dash' also has a 'read -i', so for
current Debian, the '-i' is universal. Earlier versions,
or other *nixs might not though.)
HTH...
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