Use spaces in parameter used in script called by a command

Question

I need to run a Bash command with a script calling parameters: comm1 ./script.sh param1 param2 param3. Script includes this: timeout 10 bash -c " comm2 ./param1.param3". It indicates that param1 file is in the current directory.

And it works as long as param1 is a single word. But I need it to be a file name which can have spaces. So command should be: comm1 ./script.sh "param1\ with\ space" param2 param3 . No dot and extension in file name, just spaces are problem and maybe brackets.

I don't know how to modify param1 to be able to use spaces in this case, and if script should also be modified. Thanks for help.

printf -v cmd_line '%q ' comm2 "$1" "$2" will generate a $cmd_line that's correctly quoted with spaces from $1 or $2 escaped. Thereafter, you can run timeout 10 bash -c "$cmd_line" — Charles Duffy
– Charles Duffy, Commented Jan 31, 2022 at 13:46
...however, I do agree with Kaffe that it's not obvious why you're calling an intermediary copy of bash at all, instead of timeout 10 comm2 "$1" "$2" -- when you don't wrap things in bash -c you don't need the extra escaping in the first place. — Charles Duffy
– Charles Duffy, Commented Jan 31, 2022 at 13:47
I call bash first because comm2 ./param1 param2 really is pre-comm2-param comm2 ./param1 param2 meaning command has a special parameter before, so it didn't work all without bash -c. — TimSO
– TimSO, Commented Jan 31, 2022 at 13:56
I'd need to know that your "special parameter" really is for that to make sense. A redirection? An environment variable assignment? Either way there's an option available that doesn't require an extra copy of bash (what that option is depending on the details of what the "special parameter" is). Only if it's an exported shell function wrapper do you really, unavoidably need a shell. — Charles Duffy
– Charles Duffy, Commented Jan 31, 2022 at 17:42

choroba · Accepted Answer · 2022-01-31 16:33:41Z

3

Instead of trying to quote and escape the parameters, send the parameters to bash -c.

timeout 10 bash -c 'comm2 "$@"' bash "$1" "$2"

This will set $0 to "bash" and the first two parameters to the values of the first two positional parameters of the script.

edited Jan 31, 2022 at 16:33

answered Jan 31, 2022 at 13:35

choroba

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4 Comments

Charles Duffy Over a year ago

True, but comm2 (parsed as a shell script, being the argument directly after -c) doesn't inspect $1 and $2 so they just get thrown away. Maybe you want timeout 10 bash -c 'comm2 "$@"' bash "$1" "$2"?

TimSO Over a year ago

I use parameters like this: timeout 10 bash -c ' comm2 ' ./"param1"."param3" I have to indicate to comm2 that it's a filename. I see echo of timeout 10 bash -c 'comm2' './$1.$2' which may mean that replacement is done correctly, but really it doesn't work. Comm2 doesn't open that file.

choroba Over a year ago

@CharlesDuffy: Exactly, copy-paste problem on my side.

TimSO Over a year ago

Working with comm1 ./script.sh "param1 with space" param2 param3 , thanks.

Kaffe Myers · Accepted Answer · 2022-01-31 17:52:04Z

0

I'm a bit unsure on the exact reason to call bash first.

The easiest answer is to simply skip the bash call:

timeout 10 comm2 "./param with.spaces" param2

If you want to reuse the logic in several places, make a function.

timesup() { timeout 10 "$@" ;}

timesup comm2 "./param with.spaces" param2

whatever command you throw, the function will parse it the same way

If you really need to call bash first for whatever reason, you could mix quotation:

timeout 10 bash -c "comm2 './param with.spaces' param2"

edited Jan 31, 2022 at 17:52

answered Jan 31, 2022 at 13:41

Kaffe Myers

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4 Comments

Charles Duffy Over a year ago

As command is itself a built-in command included in the shell, it might make more sense to leave the OP's distinct placeholder name in place unless you mean to instruct people to use that builtin.

Charles Duffy Over a year ago

comm is, incidentally, also a standard command)

Kaffe Myers Over a year ago

Hahaha. the first was just a miss. but comm I didn't know off!

TimSO Over a year ago

Looks simple, but somehow it does OK a few iterations and then just stalls, not sure how. I used comm1 ./script.sh "param1 with space" param2 and saw with echo this: timeout 10 bash -c 'comm2 '\''./param1 with space'\''.param2' It's all single quotes.

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