difference between ksh and POSIX sh: assigning SECONDS[1] quits

[Jdamian]

I've found this different behaviour of ksh and POSIX sh:

ksh quits the shell (or session) if an element of a *special* shell variable is tried to be initalized. "*special* shell variable" means shell variable updated internally by shell as SECONDS, RANDOM or _. Try

RANDOM[2]=45

Instead, POSIX sh allows these *special* shell variables to be arrays as ordinary variables and does not quit.

I've found a similar behaviour in Korn shell for Solaris.

[Dennis Handly]

This still aborts on 11.31. Have you contacted the Response Center? Here is a stack trace:
#0 0x0 in
#1 0x40531d0:0 in nam_putval+0x8b0
#2 0x403bf00:0 in env_namset+0x620
#3 0x403b840:0 in env_setlist+0xe0
#4 0x40379a0:0 in sh_exec+0x760
#5 0x4035170:0 in exfile+0x970
#6 0x4033ac0:0 in main+0xa50

Any reason you are trying to do that?
If you insist, you can simply unset the variable first.

[Peter Nikitka]

Hi,

in ksh it is always recommended to declare arrays explicitly - whether you use a predefined variable or not.

root@hp1[192] set -A SECONDS
root@hp1[193] SECONDS[2]=aa
root@hp1[194] print ${SECONDS[2]}
aa
root@hp1[195] print ${#SECONDS[*]}
1
root@hp1[196] uname -a
HP-UX hp1 B.11.23 U ia64 2944899503 unlimited-user license

mfG Peter

[Jdamian]

Hi Peter


Try using the variable _ instead of SECONDS.

[Peter Nikitka]

Hi Oscar,

at least for this SUN-Solaris this is NOT true (no HP-UX at hand today):

ef3nip00@malt uname -a
SunOS malt 5.10 Generic_118833-36 sun4u sparc SUNW,Sun-Fire-280R
ef3nip00@malt set -A _ aa bb cc
ef3nip00@malt echo ${_[0]}
aa

and even (in a new ksh) this works:
ef3nip00@malt echo $_
/usr/bin/ksh
ef3nip00@malt _[1]=hu
ef3nip00@malt echo ${_[*]}
/usr/bin/ksh hu

You could file a bug report - the docs tell us, that those variables loose their special meaning when manually modified, but there is no limitation on the type of the modifaction.

mfG Peter