How to quote strings in file names in zsh (passing back to other scripts)

Question

I have a script that has a string in a file name like so:

filename_with_spaces="a file with spaces"
echo test > "$filename_with_spaces"
test_expect_success "test1: filename with spaces" "
  run cat \"$filename_with_spaces\"
  run grep test \"$filename_with_spaces\"
"

test_expect_success is defined as:

test_expect_success () {
  echo "expecting success: $1"
  eval "$2"
}

and run is defined as:

#!/bin/zsh
# make nice filename removing special characters, replace space with _
filename=`echo $@ | tr ' ' _ | tr -cd 'a-zA-Z0-9_.'`.run
echo "#!/bin/zsh" > $filename
print "$@" >> $filename
chmod +x $filename
./$filename

But when I run the toplevel script test_expect_success... I get cat_a_file_with_spaces.run with:

#!/bin/zsh
cat a file with spaces

The problem is the quotes around a file with spaces in cat_a_file_with_spaces.run is missing. How do you get Z shell to keep the correct quoting?

Thanks

Answer 1

Try

run cat ${(q)filename_with_spaces}

. It is what (q) modifier was written for. Same for run script:

echo -E ${(q)@} >> $filename

. And it is not bash, you don't need to put quotes around variables: unless you specify some option (don't remember which exactly)

command $var

always passes exactly one argument to command no matter what is in $var. To ensure that some zsh option will not alter the behavior, put

emulate -L zsh

at the top of every script.

Note that initial variant (run cat \"$filename_with_spaces\") is not a correct quoting: filename may contain any character except NULL and / used for separating directories. ${(q)} takes care about it.

Update: I would have written test_expect_success function in the following fashion:

function test_expect_success()
{
    emulate -L zsh
    echo "Expecting success: $1" ; shift
    $@
}

Usage:

test_expect_success "Message" run cat $filename_with_spaces