In the old days, a "ps -e" on Linux would get you something like
warning: `-' deprecated; use `ps e', not `ps -e'
PID TTY STAT TIME COMMAND
To get that now, you need to use "oldps". The man page (which
you can still see with "man oldps") warned:
For now, ps will give you a warning if you use a `-' for a
short option, but it will still work. If you have shell
scripts which use BSD-style arguments to ps, take heed of
the warning and fix them, or else your scripts will fail
to function correctly at some point in the future. If you
want to turn off the warnings, set the I_WANT_A_BROKEN_PS
When I first saw this, it ticked me off. From time to time, I've
even made comments like:
Personally, I think bsd ps semantics are "broken", not the
other way around. But if I were putting in such a flag,
I'd call it "I_WANT_BSD_FLAGS".
Well, I was wrong. Albert
Cahalan (see the end of "man ps") set me straight:
I think Michael K. Johnson named that option, not me,
but I support the naming and the code behind it.
If you set that option, you make ps violate the POSIX and
UNIX standards. The common "ps -ef" command will not work.
(this is an ISO, IEEE, Open Group, and ANSI standard)
According to the standards, "ps -aux" is parsed the same
way as "ps -a -u x", with "x" being a username!
People who want the BSD options get them by default anyway,
with less typing. Why type "ps -aux" when "ps aux" will work?
Besides, it's more portable to leave off the "-". You can
use "ps aux" on AIX or Tru64, along with "ps -ef", but you
can't use "ps -aux" on those systems at all.
I like using both BSD and UNIX syntax, sometimes together.
ps f -ef
ps -C bash,xterm u
OK, I see the error of my ways. But.. the new ps doesn't seem to
mind using "ps -e" at all. So the warning seems not to have come
true, at least not yet.
Reading the newer "man ps", I found this :
none "Do the right thing"
aix like AIX ps
bsd like FreeBSD ps
compaq like Digital Unix ps
debian like the old Debian ps
digital like Digital Unix ps
gnu like the old Debian ps
hp like HP-UX ps
hpux like HP-UX ps
irix like Irix ps
linux deviate from Unix98 for convenience only
old like the original Linux ps
sco like SCO ps
sgi like Irix ps
sun like SunOS 4 ps
sunos like SunOS 4 ps
That made me think that if I set PS_PERSONALITY to "old" (and
exported it) that "ps -e" would act like "oldps -e", but it doesn't
(at least not on the system I tried it on). However, setting and
exporting CMD_ENV did alter the behaviour as expected, though you
don't get the "deprecated" message.
It's fun to play with the various settings. I notice that "sco"
is one of the options, though I'm not sure what effects that has.
Perhaps it causes "ps" to spawn a lawsuit?
See How "ps" works and why also.
Got something to add? Send me email.
Increase ad revenue 50-250% with Ezoic
More Articles by Tony Lawrence
Find me on Google+
© 2011-03-20 Tony Lawrence