Problems with GNU time

[Tassilo Horn]

Hi all,

I've written a small compression utility as part of my academic work. To
see how it performs, I want to compare it to some other tools (gzip,
bzip2, compress, ...). Therefore I tried using GNU time (version 1.7),
but some measures don't work for me.

A sample call looks like this:

,----[ /usr/bin/time -f "%U#%S#%p#%M" binarygxl -q -e stc.gxl test.bgxl ]
| 19.81#0.34#0#0
`----

As you can see, the format string contains those fields:

,----[ (info "(time)Time Resources") ]
| `S'
|      Total number of CPU-seconds used by the system on behalf of the
|      process (in kernel mode), in seconds.
| 
| `U'
|      Total number of CPU-seconds that the process used directly (in
|      user mode), in seconds.
`----

,----[ (info "(time)Memory Resources") ]
| `M'
|      Maximum resident set size of the process during its lifetime, in
|      Kilobytes.
|
| [snipped not used resources] 
| 
| `p'
|      Average size of the process's unshared stack, in Kilobytes.
`----

But why are the memory resources always zero? What could cause this?

This happens with all commands (gzip, bzip2, etc.), so it's no my
binarygxl app, which is that superiour that it uses no memory at
all. ;-)

If you don't know what the cause could be, but you know another tool I
could use, please leave a pointer. It would be good if it's command line
based, so that I can use it in scripts.

Kind regards and much thanks in advance,
Tassilo