Re: Yet another "stop the bash quoting" post

From: Paul Colquhoun (postmaster_at_andor.dropbear.id.au)
Date: 11/29/04 

Date: Mon, 29 Nov 2004 03:00:41 GMT

On Sun, 28 Nov 2004 19:48:22 GMT, Allen Kistler <ackistler@oohay.moc> wrote:
| rakesh sharma wrote:
|>
|> Try this:
|>
|> ##### file1.sh ####
|> #!/bin/bash -u
|> CMD="./zxc.sh \"-o'a b'\""
|> echo "\$CMD=|$CMD|"
|> eval "
|> set -x
|> $CMD
|> set +x
|> "
|> ######### end of file1.sh ##########
|>
|> ####### zxc.sh ########
|> echo "Inside the file... '$0'"
|> for arg
|> do
|> echo "arg=|$arg|"
|> done
|> ############ end of zxc.sh ###########
|>
|> Output from running the file1.sh command is:
|>
|> $CMD=|./zxc.sh "-o'a b'"|
|> + ./zxc.sh -o'a b'
|> Inside the file... './zxc.sh'
|> arg=|-o'a b'|
|> + set +x
|>
|>
|>
|> Is this what you wanted? But remember that here the argumetnt
|> contains the a real single quote.
|>
|> Even from the command line when you say:
|> command -o'a b'
|>
|> the argument doesn't contain those single quotes; they"re there to protect
|> the spaces between a and b & prevent wildcard expansions.
|> So I still feel that my previous reply is what you really need.
|>
|>
|> What you see is not what the command sees because the entity shell is
|> performing some operations silently/behind the scenes.
|>
|> command -o'A B'
|>
|> will entail 'command' being passed only 1 argument
|> "-oA B" (double quotes for emphasis not part of the argument)
|>
|> In the case I showed today, .... ok it prints -o'a b' but the argument
|> that 'command' gets from the shell contains those single quotes too.
|>
|> Unless you intend to do 2/more levels of evaling it's an error.
|
| By using set -x in the bash script and running /command/ without the
| eval, I can see that bash sees this as
| '"-oa b"'
| Assigning it to CMD and using eval, I get
| '-o'\''a b'\'''
|
| Unfortunately the binary (sendmail BTW, just to make it real) is still
| not recognizing either as a switch, probably because they start with a
| quote, not a dash. It interprets, e.g., '-oa b' as a recipient, not an
| option. The same problem exists for any binary that takes switches, not
| just sendmail, though.
|
| Maybe the better way to pose the problem is:
| Is there any way to make bash be satisfied that the quotes around a
| space are *not* the outermost characters in a string.
| -o'a b' still has quotes around the space, after all, which is probably
| why it works fine on the command line.

What sendmail option needs a space in it's parameters?

Here are some bash scripts I wrote, and their output. Most quoting
options seem to follow through correctly, without having to get very
convoluted.

$ cat example_command
#!/bin/bash

echo '======================'
[ "$0" ] && echo "\$0 = '$0'"
[ "$1" ] && echo "\$1 = '$1'"
[ "$2" ] && echo "\$2 = '$2'"
[ "$3" ] && echo "\$3 = '$3'"
[ "$4" ] && echo "\$4 = '$4'"
[ "$5" ] && echo "\$5 = '$5'"
[ "$6" ] && echo "\$6 = '$6'"
[ "$7" ] && echo "\$7 = '$7'"
[ "$8" ] && echo "\$8 = '$8'"
[ "$9" ] && echo "\$9 = '$9'"
echo '======================'
echo

$ cat example_wrapper
#!/bin/bash

./example_command -oa b
./example_command '-oa b'
./example_command -o'a b'
./example_command -oa\ b

CMD="./example_command -oa b"; eval $CMD
CMD="./example_command '-oa b'"; eval $CMD
CMD="./example_command -o'a b'"; eval $CMD
CMD="./example_command -oa\ b"; eval $CMD
CMD="./example_command -oa\\\ b"; eval $CMD

$ ./example_wrapper
======================
$0 = './example_command'
$1 = '-oa'
$2 = 'b'
======================

======================
$0 = './example_command'
$1 = '-oa b'
======================

======================
$0 = './example_command'
$1 = '-oa b'
======================

======================
$0 = './example_command'
$1 = '-oa b'
======================

======================
$0 = './example_command'
$1 = '-oa'
$2 = 'b'
======================

======================
$0 = './example_command'
$1 = '-oa b'
======================

======================
$0 = './example_command'
$1 = '-oa b'
======================

======================
$0 = './example_command'
$1 = '-oa b'
======================

======================
$0 = './example_command'
$1 = '-oa\'
$2 = 'b'
====================== 

-- 
Reverend Paul Colquhoun, ULC.    http://andor.dropbear.id.au/~paulcol
     Asking for technical help in newsgroups?  Read this first:
        http://catb.org/~esr/faqs/smart-questions.html#intro

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