The dtexec code assumes that fstat reports pipe's readable chars.
Linux always reports 0 for st_size of a pipe.
Instead read one character when select reports readable.
Note EOF when select says readable but read returns 0.
Patch from Pascal Stumpf <Pascal.Stumpf@cubes.de>
The official POSIX name for this signal is SIGCHLD. Linux probably
has SIGCLD only for SysV compatibility, but BSD does not.