On Mon, Aug 28, 2006 at 01:33:59AM +0200, Ingo Schwarze wrote:
| > Please now try `if ! false; then echo true; fi`.
| > Why does my shell eat muchos CPU & RAM after such a short pipeline?
|
| schwarze@idefix $ uname -a
| OpenBSD idefix 3.9 GENERIC#617 i386
| schwarze@idefix $ /bin/ksh
| $ date
| Mon Aug 28 01:28:07 CEST 2006
| $ if ! false; then echo true; fi
| true
| $ date
| Mon Aug 28 01:28:12 CEST 2006
| $ date; ( if ! false; then echo true; fi ); date
| Mon Aug 28 01:28:20 CEST 2006
| true
| Mon Aug 28 01:28:20 CEST 2006
| $ time ( if ! false; then echo true; fi )
| true
| 0m0.01s real 0m0.00s user 0m0.01s system
| $ time ( echo `if ! false; then echo true; fi` )
| true
| 0m0.04s real 0m0.00s user 0m0.02s system
| $ exit
|
| Sorry, cannot reproduce.
| Works for me (on OpenBSD 3.9-release).

Now it takes quite a bit of time before it actually reaches this.
Searching the manpage a bit more, I found another reference to '!'.

$ set +o csh-history
$ time ( if ! false; then echo true; fi )
true
0m0.00s real 0m0.00s user 0m0.01s system
$ set -o csh-history
$ time ( if ! false; then echo true; fi )
/bin/ksh: internal error: unable to allocate memory

Since I set csh-history in my .kshrc, this option is set in all my
shells. I don't think this is intended behaviour, but if it is, it
probably should be documented in the manpage.

Cheers,

Paul 'WEiRD' de Weerd

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