0001380: /usr/bin/[ gives "[: ]: unknown operand" message

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Reproducibility

Date Submitted

Last Update

0001380

[BusyBox] Other

major

always

06-05-07 08:44

06-08-07 00:34

Reporter

dmaizer

View Status

public

Assigned To

BusyBox

Priority

normal

Resolution

fixed

Status

closed

Product Version

1.4.x

Summary

0001380: /usr/bin/[ gives "[: ]: unknown operand" message

Description

We are working in an Apache (httpd 2.2.3) suexec CGI scripts environment and our CGI scripts need to provide full paths to all applets/programs used, so we have something like the following in the CGI script:

if /usr/bin/[ $# -lt 1 ]; then
   /bin/echo "sitediag: too few arguments"
   /bin/echo "Try sitediag --help for more information"
   exit 1
fi

However - this gives the error:
[: ]: unknown operand

Meaning that the "]" closing bracket is being recognized as an unknown operand. But of course this bracket is needed to close the test...

If we remove the /usr/bin prefix from [ - then it works and gives the expected echo messages above.

I tried looking at busybox code (being no expert of that code) and found the following in coreutils/test.c:

    if (*t_wp != NULL && *++t_wp != NULL) {
        bb_error_msg("%s: unknown operand", *t_wp);
        return 2;
    }

My guess is that somehow using the pathname causes that condition above to be true, but I haven't been able to find out why yet (I started looking from ash.c and "lower" to see why this happens, but haven't been able to find anything meaningful so far - hopefully someone who knows the code better can provide a clue or a fix.

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Notes
(0002442) dmaizer 06-05-07 08:45	We use version 1.4.2 of busybox...

(0002443) bernhardf 06-05-07 09:26	confirmed. As a quick workaround, just use "test" instead of "[" or "[[". I will also note, that the check for surplus args is borked (as you note) since some closing brackets are a legit character to see -- IFF we were called as "[" one and two otherwise. For the sake of code-size, there is currently no checking for the correct number of closing brackets, so just omitting any closing bracket bypasses the reported behaviour.

(0002464) vda 06-08-07 00:34	Fixed in rev 18775, thanks

Issue History
Date Modified	Username	Field	Change
06-05-07 08:44	dmaizer	New Issue
06-05-07 08:44	dmaizer	Status	new => assigned
06-05-07 08:44	dmaizer	Assigned To	=> BusyBox
06-05-07 08:45	dmaizer	Note Added: 0002442
06-05-07 09:26	bernhardf	Note Added: 0002443
06-08-07 00:34	vda	Status	assigned => closed
06-08-07 00:34	vda	Note Added: 0002464
06-08-07 00:34	vda	Resolution	open => fixed