Bash is back

I had an other painful experience with bash scripts today.

All I wanted to do was to create a cron task that updates some files in a folder, compresses and uploads these files on a web site using ftp.

As before, the curl part was problematic, when used in conjunction with variables.

But this time, I've found this answer in a thread. Turns out that when you declare:

→ FOO='a b "c d"'

echo $FOO will work as expected, but showargs $FOO will list these parameters:

→ showargs $FOO
Program name: showargs
Parameter  1: a
Parameter  2: b
Parameter  3: "c
Parameter  4: d"

4 parameters instead of the expected 3, double quotes loosing their meaning and a text split by spaces.

showargs

showargs is a simple C executable that lists the different parameters of a bash command. Here is its code:

#include <stdio.h>

int main (int argc, char *argv[]) {
        printf("Program name: %s\n", argv[0]);
        for (int i=1; i<argc; i++)
                printf("Parameter %2d: %s\n", i, argv[i]);

        return 0;
}

Use gcc showargs.c -o showargs to compile, and you'll get a pretty cool debugging tool. Simply preprend it in front of the failing command in your script to list its actual parameters.

This allowed me to fix my curl syntax (by splitting a variable into two, bash black magic).

When I'm ready, I'll try to debug the bash REST test I abandoned few weeks ago.