CODEWITHSUNDEEP
bashparsingarguments
kiri
kiri

Reputation: 2632

Parse a variable as if it were parameters?

Is there a way in Bash (without calling a 2nd script) to parse variables as if they were command line arguments? I'd like to be able to group them by quotes and such.

Example:

this="'hi there' name here"

for argument in $this; do
    echo "$argument"
done

which should print (but obviously doesn't)

hi there
name
here

Upvotes: 2

Views: 229

Answers (3)

chepner
chepner

Reputation: 531055

Don't store the arguments in a string. Arrays were invented for this purpose:

this=('hi there' name here)

for argument in "${this[@]}"; do
    echo "$argument"
done

It is highly recommended that you use this approach if you have control over this. If you don't, that is even more reason not to use eval, since unintended commands can be embedded in the value of this. For example:

$ this="'hi there'); echo gotcha; foo=("
$ eval args=($this)
gotcha

Less nefarious is something as simple as this="'hi there' *". eval will expand the * as a pattern, matching every file in the current directory.

Upvotes: 2

anubhava
anubhava

Reputation: 785058

Using gsed -r:

echo "$this" | gsed -r 's/("[^"]*"|[^" ]*) */\1\n/g'
"hi there"
name
here

Using egrep -o:

echo "$this" | egrep -o '"[^"]*"|[^" ]+'
"hi there"
name
here

Pure BASH way:

this="'hi there' name here"
s="$this"
while [[ "$s" =~ \"[^\"]*\"|[^\"\ ]+ ]]; do
    echo ${BASH_REMATCH[0]}
    l=$((${#BASH_REMATCH[0]}+1))
    s="${s:$l}"
done

"hi there"
name
here

Upvotes: 1

kiri
kiri

Reputation: 2632

I worked out a half-answer myself. Consider the following code:

this="'hi there' name here"

eval args=($this)

for arg in "${args[@]}"; do
    echo "$arg"
done

which prints the desired output of 

hi there
name
here

Upvotes: 2

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