Re: /proc/<pid>/cmdline

Andries.Brouwer@cwi.nl
Sun, 14 Jul 1996 01:04:05 +0200


Kai Schulte:

: On Thu, 11 Jul 1996, Jason Tyler wrote:

:: ~; cat /proc/248/cmdline | cat -v
:: xterm^@-ls^@-sl^@500^@-font^@7x13^@-sb^@-bg^@black^@-fg^@white
::
:: The obvious 'cat -v /proc/248/cmdline' doesn't work, not for me at
:: least -- anyone know why?

: cat -v works directly on proc here with

: cat from GNU fileutils 1.9 a.out, libc 4.6.27, linux-2.0.5
: cat from GNU fileutils 1.14 a.out, libc 4.6.27, linux-2.0.5
: cat from GNU fileutils 1.9 elf, libc 5.2.18, linux-2.0.4

: Hard to find out where things changed without being able to reproduce this
: behaviour... maybe you have more recent libs?

# ls -l /bin/cat /proc/self/cmdline
-rwxr-xr-x 1 root other 4376 Sep 8 1992 /bin/cat*
-r--r--r-- 1 aeb other 0 Jul 14 00:54 /proc/self/cmdline
# cat -v /proc/self/cmdline
#

Also very old cats show this behaviour.
I think the reason is that the kernel shows this file as having length 0,
and this confuses some versions of cat (when given the -v option).

Andries