Rene Scharfe wrote:
Bill Davidsen schrieb:
On the theory that my first post got lost, why use /usr/bin/env at
all, when bash already does that substitution? To support people who
use other shells?
ie.: FOO=xx perl -e '$a=$ENV{FOO}; print "$a\n"'
/usr/bin/env is used in scripts in the shebang line (the very first line
of the script, starting with "#!", which denotes the interpreter to use
for that script) to make a PATH search for the real interpreter.
Some folks keep their python (or Perl, or Bash etc.) in /usr/local/bin
or in $HOME, that's why this construct is needed at all.
Changing environment variables is not the goal, insofar this usage
exploits only a side-effect of env. It is portable in practice because
env is in /usr/bin on most modern systems.
So you could replace this first line of a bash script:
#!/usr/bin/env python
with this:
#!python
except that the latter doesn't work because you need to specify an
absolute path there. :]
Assuming that you want the PATH search rather than a symlink in
/usr/bin, of course. This opens the door to forgetting you just loaded
the CVS daily of python into your test directory and doing an unplanned
test of alpha software, but if people think the application should work
with non-standard tool chains, and realize it has possible unwanted
effects, that's a design decision.
--
-bill davidsen ([email protected])
"The secret to procrastination is to put things off until the
last possible moment - but no longer" -me
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