Bug 711654

Description of problem:
Although it is possible to have a PATH environment definition in a crontab other environment variables on the rhs are not expanded

Version-Release number of selected component (if applicable):
cronie-1.4.7-3

How reproducible:
Always

Steps to Reproduce:
1. create this C program (x.c) and save compiled result in ~/bin/x:
#include <stdio.h>
#include <stdlib.h>

int
main(int argc, char **argv)
{
    execvp(argv[1], &argv[1]);
    fprintf(stderr, "Exec failed\n");
    exit(1);
}

2. create this crontab entry and wait for it to run:
      PATH=$HOME/bin
      * * * * * x /bin/pwd </dev/null

3. create this crontab entry and wait for it to run:
      PATH=~/bin
      * * * * * x /bin/pwd </dev/null

4. create this crontab entry and wait for it to run:
      PATH=$HOME/bin
      * * * * * /usr/bin/xargs x /bin/pwd </dev/null

5. create this crontab entry and wait for it to run:
      PATH=~/bin
      * * * * * /usr/bin/xargs x /bin/pwd </dev/null

6. create this crontab entry and wait for it to run:
      PATH=/home/users/<YOU>/bin
      * * * * * /usr/bin/xargs x  /bin/pwd </dev/null

Actual results:
2. fail: sh: /bin/sh: x: command not found
3. ok: /home/users/<YOU>
4. fail: /usr/bin/xargs: x: No such file or directory
5. fail: /usr/bin/xargs: x: No such file or directory
6. ok: /home/users/<YOU>

Expected results:
2. ok: /home/users/<YOU>
3. ok: /home/users/<YOU>
4. ok: /home/users/<YOU>
5. ok: /home/users/<YOU>
6. ok: /home/users/<YOU>

Additional info:
The problem is to do with expansion of either HOME or ~ and the use of execvp. While execvp duplicates the actions of the shell somewhat it does not substitute  for $HOME or ~. But crond executes crontab lines using "sh -c" which is why case 3 works, and case 2 fails (the actual PATH contains an unexpanded $HOME).

Users are mostly used to using constructs such as "PATH=$HOME/bin" which work because the shell expands the rhs and stores the expanded PATH setting. It can be difficult to see that the internal PATH contains an unexpanded variable because naive 'echo $PATH' will also expand any embedded unexpanded variable.

So to be consistent it would be best if crond expanded the rhs of a PATH setting so as to properly substitute for ~ and environment variables.  Because it certainly seems very weird for this to not happen.  It defies common sense. It contradicts all other known cases where a PATH can be set