CODEWITHSUNDEEP
bash
labyrinth
labyrinth

Reputation: 13966

Is it possible to use the builtin "read" with local, readonly, or declare options?

When using the bash builtin "read" to set a variable from user input, is it possible to set that variable as local (in a function), readonly, or use various declare options (e.g. declare -i)?

If not, how do you deal robustly with variables that are read from user input? I'd rather minimize globals that are lying around in my scripts.

Upvotes: 3

Views: 409

Answers (2)

hek2mgl
hek2mgl

Reputation: 158220

If you want to variable to be local you may declare the variable before calling read?:

local input
read input

If it should be an array, read supports the -a switch:

local arr
read -a arr
<type>foo bar 123

readonly variable can't be passed to read. This is because read will attempt to write the input data to the variable:

readonly foo
read foo
<type> ...

Output:

test.sh: line 2: foo: readonly variable

You could use this workaround: (but check @gniourf_gniourf's comment)

local tmp
read tmp

readonly variable="$tmp"

You might also read into integer vars which have been declared using -i. Any non numeric input would be interpreted as 0 in this case:

declare -i number
read number
<type>ABC

echo "$number" # 0

declare -i number
read number
<type>123

echo "$number" # 123

Upvotes: 1

konsolebox
konsolebox

Reputation: 75588

You can set the readonly attribute on later time:

local A
read A
readonly A
A=1 ## error

Upvotes: 1

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