CODEWITHSUNDEEP
bashpython-2.7quotes
Aran-Fey
Aran-Fey

Reputation: 43276

Bash: pass variable as a single parameter / shell quote parameter

I'm writing a bash script which has to pass a variable to another program:

./program $variable

The problem is, it is absolutely necessary for $variable to be passed as a single parameter, which isn't the case if it contains whitespace.

variable=Hello World
./program $variable
-> program receives two arguments: 'Hello' 'World'

Quoting it doesn't do anything at all (well done, bash devs):

variable=Hello World
./program "$variable"
-> program receives: 'Hello' 'World'

Double quoting it does crazy stuff (well done, bash devs):

variable=Hello World
./program "'$variable'"
-> program receives: "'Hello" "World'"

Is there an easy way to do this? Heck, is there a way to do this at all?

Update: Okay, since the problem doesn't seem to be bash, here's some additional info. The program I'm passing arguments to is a python script. Without modifying the arguments in any way, I get

print sys.argv
-> ['/usr/bin/program', "'Hello", "World'"]

How can I fix that?

Edit: No, I haven't tried

variable="Hello World"

because I never declare $variable. It's not being declared inside my bash function and I'm not allowed to modify it.

Edit: Okay, I got it to work that way.

local temp="$variable"
./program "$temp"

I'd like to know why it works that way and not any other way, though.

Upvotes: 3

Views: 2676

Answers (5)

Daniel Voina
Daniel Voina

Reputation: 3215

Have a look on http://tldp.org/LDP/Bash-Beginners-Guide/html/sect_03_04.html .

The problem is that the expansion of variables is done before of the command line parameters hence your behavior.

You might work it arround with setting IFS to something weird as 

IFS='###' V='foo bar baz'; ./program $V

Upvotes: 1

morgents
morgents

Reputation: 505

When you call your script pass the arguments within quotes.

Example script:

#!/bin/bash
for arg in "$@"; do
 echo "arg: $1";
 shift;
done

When you call it with:

./program "parameter with multiple words" parameter2 parameter3 "another parameter"

The output should be:

arg: parameter with multiple words
arg: parameter2
arg: parameter3
arg: another parameter

Upvotes: 1

Vijay
Vijay

Reputation: 67301

did you try with var="hello world"?

i tried this in my solaris box.

> setenv var "hello world"
> cat temp.sh
#!/bin/sh

echo $1
echo $2
> ./temp.sh "$var"
hello world

>

as you can see the $2 is not printed.$var is considered as only one argument.

Upvotes: 1

Nahuel Fouilleul
Nahuel Fouilleul

Reputation: 19325

The problem seems to be inside the "program"

variable="Hello World"    # quotes are needed because of the space
./program "$variable"     # here quotes again

and inside the program

echo "program received $# arguments:" 
i=1
for arg in "$@"      # again quotes needed
do echo "arg $((i=i+1)): '$arg'"    # and again
done

Upvotes: 0

ShankarG
ShankarG

Reputation: 1165

This is almost certainly a problem in the way you are reading the variable in your program.
For instance suppose this is your script (just one line for testing):

echo "$1"

Let's call it echo.sh. If you run echo.sh "test best", you will get test best.

But if your program says

echo $1

you might get behaviour like what you're seeing.

Upvotes: 0

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