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[perl #107368] perl -e '#!perl -s' is weird

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Father Chrysostomos
January 1, 2012 13:12
[perl #107368] perl -e '#!perl -s' is weird
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# New Ticket Created by  Father Chrysostomos 
# Please include the string:  [perl #107368]
# in the subject line of all future correspondence about this issue. 
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The subject can be understood in both senses. :-)

Running perl with -e '#!perl -s' results in erratic behaviour.  Normally, @ARGV begins with the first argument that perl itself does not interpret:

$ perl -le 'print("@ARGV")' 1
$ perl -sle 'print("@ARGV");' -e 'print "styll here"' -- -foo=bar 1
styll here

But -e '#!perl -s' causes the argument to a subsequent -e to be included in @ARGV magically:

$ perl -le '#!perl -s' -e 'print("@ARGV")' 1
print("@ARGV") 1

Even including switches like -w that perl itself is interpreting:

$ perl -le '#!perl -s' -e 'print("@ARGV"); 3' -w a
Useless use of a constant in void context at -e line 2.
Name "main::e" used only once: possible typo at -e line 1.
print("@ARGV"); 3 -w a

Unless the argument to -e is part of the same command-line argument:

$ perl -le '#!perl -s' -e'print("@ARGV");' -w
Name "main::eprint("@ARGV");" used only once: possible typo at -e line 1.
Name "main::w" used only once: possible typo at -e line 1.

Those ‘used once’ warning suggest that -s is parsing the switches to perl itself.  And then perl is parsing them, too.

Let’s see:

$ perl -le '#!perl -s' -e'$a += 1; print ${"e\$a +"};'
 1; print ${"e\$a +"};

I wonder if I could write a quine with this. :-)
Site configuration information for perl 5.15.6:

Configured by sprout at Thu Dec 29 12:39:18 PST 2011.

Summary of my perl5 (revision 5 version 15 subversion 6) configuration:
  Snapshot of: 7d9189d8cb23dc30b986d15850dce6adf8b74772
    osname=darwin, osvers=10.5.0, archname=darwin-thread-multi-2level
    uname='darwin pint.local 10.5.0 darwin kernel version 10.5.0: fri nov 5 23:20:39 pdt 2010; root:xnu-1504.9.17~1release_i386 i386 '
    config_args='-de -Dusedevel -Dmad -Duseithreads'
    hint=recommended, useposix=true, d_sigaction=define
    useithreads=define, usemultiplicity=define
    useperlio=define, d_sfio=undef, uselargefiles=define, usesocks=undef
    use64bitint=undef, use64bitall=undef, uselongdouble=undef
    usemymalloc=n, bincompat5005=undef
    cc='cc', ccflags ='-fno-common -DPERL_DARWIN -fno-strict-aliasing -pipe -fstack-protector -I/usr/local/include',
    cppflags='-fno-common -DPERL_DARWIN -fno-strict-aliasing -pipe -fstack-protector -I/usr/local/include'
    ccversion='', gccversion='4.2.1 (Apple Inc. build 5664)', gccosandvers=''
    intsize=4, longsize=4, ptrsize=4, doublesize=8, byteorder=1234
    d_longlong=define, longlongsize=8, d_longdbl=define, longdblsize=16
    ivtype='long', ivsize=4, nvtype='double', nvsize=8, Off_t='off_t', lseeksize=8
    alignbytes=8, prototype=define
  Linker and Libraries:
    ld='env MACOSX_DEPLOYMENT_TARGET=10.3 cc', ldflags =' -fstack-protector -L/usr/local/lib'
    libpth=/usr/local/lib /usr/lib
    libs=-ldbm -ldl -lm -lutil -lc
    perllibs=-ldl -lm -lutil -lc
    libc=, so=dylib, useshrplib=false, libperl=libperl.a
  Dynamic Linking:
    dlsrc=dl_dlopen.xs, dlext=bundle, d_dlsymun=undef, ccdlflags=' '
    cccdlflags=' ', lddlflags=' -bundle -undefined dynamic_lookup -L/usr/local/lib -fstack-protector'

Locally applied patches:

@INC for perl 5.15.6:

Environment for perl 5.15.6:
    LANGUAGE (unset)
    LD_LIBRARY_PATH (unset)
    LOGDIR (unset)
    PERL_BADLANG (unset)

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