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> Marc Feeley <feeley@xxxxxxxxxxxxxxxx> writes:
> > #! /usr/bin/env script-interpreter
>
> > Anybody have experience, or comments about this? Is /usr/bin/env
> > "standard" or POSIX?
>
> from the Solaris 2.6 man page:
>
> /usr/bin/env
> If env executes commands with arguments, it uses the default
> shell /usr/bin/sh (see sh(1)).
>
> So arguably more graceful looking than the traditional shell
> trampoline, but effectively the same thing...
I just measured the run time for the following three script
structures:
script s1:
#! /u/feeley/gambc40a5/gsi/gsi
(exit)
script s2:
#! /bin/sh
"exec" "gsi" "$0" "$@"
(exit)
script s3:
#! /usr/bin/env gsi
(exit)
using Gambit on a RH Linux 1 GHz Athlon system (results of "time"
below). It seems that the /usr/bin/env approach is just as fast as
specifying the absolute path of the interpreter (about 0.01 second to
start and exit the interpreter compared to about 0.05 second when
using /bin/sh). So perhaps the use of /bin/sh by /usr/bin/env is
specific to Solaris (or maybe just non Linux systems).
Marc
% time ./s1 # 5 times
0.000u 0.010s 0:00.01 100.0% 0+0k 0+0io 451pf+0w
0.000u 0.010s 0:00.01 100.0% 0+0k 0+0io 451pf+0w
0.010u 0.000s 0:00.01 100.0% 0+0k 0+0io 451pf+0w
0.000u 0.010s 0:00.01 100.0% 0+0k 0+0io 451pf+0w
0.010u 0.000s 0:00.01 100.0% 0+0k 0+0io 451pf+0w
% time ./s2 # 5 times
0.000u 0.030s 0:00.07 42.8% 0+0k 0+0io 659pf+0w
0.000u 0.010s 0:00.05 20.0% 0+0k 0+0io 659pf+0w
0.020u 0.000s 0:00.05 40.0% 0+0k 0+0io 659pf+0w
0.000u 0.020s 0:00.05 40.0% 0+0k 0+0io 659pf+0w
0.010u 0.010s 0:00.05 40.0% 0+0k 0+0io 659pf+0w
% time ./s3 # 5 times
0.000u 0.020s 0:00.01 200.0% 0+0k 0+0io 556pf+0w
0.000u 0.010s 0:00.01 100.0% 0+0k 0+0io 556pf+0w
0.010u 0.000s 0:00.01 100.0% 0+0k 0+0io 556pf+0w
0.010u 0.000s 0:00.01 100.0% 0+0k 0+0io 556pf+0w
0.000u 0.010s 0:00.01 100.0% 0+0k 0+0io 556pf+0w