Calling execve bash on bash scripts can't find arguments - c

Question

I have two (Ubuntu Linux) bash scripts which take input arguments. They need to be run simultaneously. I tried execve with arguments e.g.
char *argv[10] = { "/mnt/hgfs/F/working/script.sh", "file1", "file2", NULL };
execve(argv[0], argv, NULL)
but the bash script can't seem to find any arguments at e.g. $0, $1, $2.
printf "gcc -c ./%s.c -o ./%s.o\n" $1 $1;
gcc -c ./$1.c -o ./$1.o -g
exit 0;
output is gcc -c ./main.c -o ./main.o
and then a lot of errors like /usr/include/libio.h:53:21: error: stdarg.h: No such file or directory
What's missing?

Answer 1

Does your script start with the hashbang line? I think that's a must, something like:
#!/bin/bash
For example, see the following C program:
#include <stdio.h>
#include <unistd.h>
char *argv[10] = { "./qq.sh", "file1", NULL };
int main (void) {
int rc = execve (argv[0], argv, NULL);
printf ("rc = %d\n", rc);
return 0;
}
When this is compiled and run with the following qq.sh file, it outputs rc = -1:
echo $1
when you change the file to:
#!/bin/bash
echo $1
it outputs:
file1
as expected.
The other thing you need to watch out for is with using these VMWare shared folders, evidenced by /mnt/hgfs. If the file was created with a Windows-type editor, it may have the "DOS" line endings of carriage-return/line-feed - that may well be causing problems with the execution of the scripts.
You can check for this by running:
od -xcb /mnt/hgfs/F/working/script.sh
and seeing if any \r characters appear.
For example, if I use the shell script with the hashbang line in it (but appen a carriage return to the line), I also get the rc = -1 output, meaning it couldn't find the shell.
And, now, based on your edits, your script has no trouble interpreting the arguments at all. The fact that it outputs:
gcc -c ./main.c -o ./main.o
is proof positive of this since it's seeing $1 as main.
The problem you actually have is that the compiler is working but it cannot find strdarg.h included from your libio.h file - this has nothing to do with whether bash can see those arguments.
My suggestion is to try and compile it manually with that command and see if you get the same errors. If so, it's a problem with what you're trying to compile rather than a bash or exec issue.
If it does compile okay, it may be because of the destruction of the environment variables in your execve call.