bash script problem: preserving quotes from arguments

[avishay]

I am trying to write a wrapper for a program (cvs) using bash. At the end of the script, I need to call the original program with the command-line arguments that were passed to the script ($@). The problem is that some of the arguments have multiple words inside quotes (such as -m "this is a message"). If I do "program $@", then the quotes aren't passed to the program, and it can't parse the options. I have tried putting quotes around $@, and using $* as well, but I couldn't get bash to do what I want. Any suggestions?

Here is the code in case it will help you. Even though I save the arguments in $OPTIONS, I get the same results when using $@ or $* directly.

#!/bin/sh

#cvs [ cvs_options ] cvs_command [ command_options ] [ command_args ]

OPTIONS="$*"

# Strip off cvs_options
until [ -z "$1" ]
do
        if [ "${1:0:1}" = "-" ] ; then
                if [ $1 = "-b" -o $1 = "-d" -o $1 = "-e" -o $1 = "-z" ] ; then
                        shift
                fi
                shift
                continue
        fi
        break
done
if [ -z "$1" ] ; then
        cvs $OPTIONS    #No options? Let CVS deal with it...
        exit $?
fi

# Check cvs_command, execute it if not commit
if [ "$1" != "commit" ] ; then
        cvs $OPTIONS
        exit $?
fi

# Check if files were given
#[-lnR] [-m 'log_message' | -f file] [-r revision] [files...]
shift
until [ -z "$1" ]
do
        if [ "${1:0:1}" = "-" ] ; then
                if [ $1 = "-f" -o $1 = "-r" -o $1 = "-m" ] ; then
                        shift
                fi
                shift
                continue
        fi
        break
done
if [ ! -z "$1" ] ; then
        cvs $OPTIONS
        exit $?
fi

# Read cvs status
FILES=`cvs -n -q update`

# Print warning
echo "Your commit will include/exclude the following files:"
echo "$FILES"
echo

# Get answer
ans="?"
until [ "$ans" = "y" -o "$ans" = "n" ]
do
        echo "Are you sure you want to commit? [y/n]"
        read ans
done

# Perform command if "y"
if [ "$ans" = "n" ] ; then
        echo "Not executing commit (aren't you happy you used this script?)"
else
        cvs $OPTIONS
fi

[birdman]

Could you use $1, $2 etc and build up $OPTIONS using a for loop and some double quotes? (You will have to escape the double quotes inside OPTIONS with a \)

All the best

[avishay]

Could you use $1, $2 etc and build up $OPTIONS using a for loop and some double quotes? (You will have to escape the double quotes inside OPTIONS with a \)

All the best

It's a pain, and I didn't think it would work, so I didn't try. I'll give it a shot though. Will update with results.

Thanks.

[avishay]

I managed to recreate $OPTIONS. It's pretty hacky, but maybe it's good enough. When I print $OPTIONS, I see the quotes where they should be. Unfortunately, when I execute `cvs $OPTIONS`, it still behaves as if the quotes weren't there. Here is the code that I added to the beginning of the script:

countargs () {
        return $#
}

for (( i = 1; i <= $# ; i++ ))
do
        eval VAR=\$$i
        countargs $VAR
        words=$?
        if [ "$words" -ge "2" ] ; then
                OPTIONS="$OPTIONS \"$VAR\""
        else
                OPTIONS="$OPTIONS $VAR"
        fi
done

[birdman]

Does it work when you type in the parameters using double quotes without the script? (i haven't used cvs before)

You could try single quotes also - apart from that I am a little stuck as to why this wouldn't work.

[avishay]

Does it work when you type in the parameters using double quotes without the script? (i haven't used cvs before)

You could try single quotes also - apart from that I am a little stuck as to why this wouldn't work.

Single quotes didn't work either. Here is a similar script, grepwrap.sh, that uses grep instead of cvs:

#!/bin/sh

countargs () {
        return $#
}

for (( i = 1; i <= $# ; i++ ))
do
        eval VAR=\$$i
        countargs $VAR
        words=$?
        if [ "$words" -ge "2" ] ; then
                OPTIONS="$OPTIONS \"$VAR\""
        else
                OPTIONS="$OPTIONS $VAR"
        fi
done

echo $OPTIONS
grep $OPTIONS

Here is what happens from the command line:
$ echo "hello 1 there" > foo
$ ./grepwrap.sh "hello there" foo
"hello there" foo
grep: there": No such file or directory
$ grep "hello there" foo
$

So the quotes are in OPTIONS now, but they aren't being interepreted correctly.

[birdman]

Looked at this and cannot find an answer (I have even tried hex and octal but to no avail)

I was looking for some way to see if we can store the not already interpreted double quotation mark, as I believe your problem lies in the fact that the double quote is already text and is interpreted by the shell as such. This is tough.

Any bash gurus out there?

[drl]

Hi.

I think $@ will do what you wish, but you'll need to invoke the magic string that includes quotes, namely

"$@"

Here's a driver script and a small script that simulates what I take your script to be. I use ":" to put markers around strings so that I can see the boundaries, including spaces:

#!/bin/bash

# @(#) drive    demo arg processing.

./s1 hello

./s1 "hello world"

./s1 "first phrase" "second phrase"

And here is script it calls

#!/bin/bash

# @(#) s1       Show argument processing.

echo
echo " Args plain"
echo :$*:

echo
echo ' Args from "$*" (note quotes)'
i=1
for arg in "$*"
do
        echo "arg $i is :$arg:"
        let "i+=1"
done

echo
echo ' Args from "$@" (note quotes)'
echo :"$@":
i=1
for arg in "$@"
do
        echo "arg $i is :$arg:"
        let "i+=1"
done

The output

% ./drive 

 Args plain
:hello:

 Args from "$*" (note quotes)
arg 1 is :hello:

 Args from "$@" (note quotes)
:hello:
arg 1 is :hello:

 Args plain
:hello world:

 Args from "$*" (note quotes)
arg 1 is :hello world:

 Args from "$@" (note quotes)
:hello world:
arg 1 is :hello world:

 Args plain
:first phrase second phrase:

 Args from "$*" (note quotes)
arg 1 is :first phrase second phrase:

 Args from "$@" (note quotes)
:first phrase second phrase:
arg 1 is :first phrase:
arg 2 is :second phrase:

See positional argument section in man bash for more details. If necessary in your situation, you could then enclose $1, $2 in quotes to preserve the spaces to use as arguments to another script ... cheers, drl

[avishay]

"$@" did the trick. I was still unable to reconstruct it properly, so I used a counter for the parameters instead of shifting and using $1. Whenever I had to call cvs, I did:

cvs "$@"

Thanks to both of you for your help.

[timcharper]

I was writing an SSH wrapper script, and for the life of me could not get quoted arguments to be passed through properly.

I finally found a solution involving awk and escaping EVERY character of EVERY argument:

#!/bin/sh
CMD=""

for (( i = 1; i <= $# ; i++ )); do
  eval ARG=\$$i
  CMD="$CMD $(echo "$ARG" | awk '{gsub(".", "\\\\&");print}')"
done

ssh my_machine cd /my/path \&\& RAILS_ENV=production $CMD

Surprisingly, this is quite bullet broof, and properly escapes strings and preserves arguments like:

./remote.sh grep "hello there" . -R
./remote.sh grep "So I says to the typewriter, \"Hey, I'm in quotes\"" . -R
./remote.sh grep "\"" . -R