Read a variable in bash with a default value
In Bash 4:
name="Ricardo"
read -e -i "$name" -p "Please enter your name: " input
name="${input:-$name}"
This displays the name after the prompt like this:
Please enter your name: Ricardo
with the cursor at the end of the name and allows the user to edit it. The last line is optional and forces the name to be the original default if the user erases the input or default (submitting a null).
You can use parameter expansion, e.g.
read -p "Enter your name [Richard]: " name
name=${name:-Richard}
echo $name
Including the default value in the prompt between brackets is a fairly common convention
What does the :-Richard
part do? From the bash manual:
${parameter:-word}
If parameter is unset or null, the expansion of word is substituted. Otherwise, the value of parameter is substituted.
Also worth noting that...
In each of the cases below, word is subject to tilde expansion, parameter expansion, command substitution, and arithmetic expansion.
So if you use webpath=${webpath:-~/httpdocs}
you will get a result of /home/user/expanded/path/httpdocs
not ~/httpdocs
, etc.
read -e -p "Enter Your Name:" -i "Ricardo" NAME
echo $NAME
Notes:
- This option requires bash 4 or higher (
bash --version
) - On macos, install current
bash
using homebrew - brew.sh -e
and-i
work together:-e
usesreadline
,-i
inserts text usingreadline
- bash 4+ manual page for
read
- linuxcommand.org