Perl system() function works sometimes.

[Reini Urban]

On Fri, Jan 27, 2012 at 3:50 PM, Gary E. Barnes wrote:
> perl -e 'system ("/bin/ls -l /tmp");'                   # still works
> perl -e 'system ("/bin/ls -l /tmp > /tmp/xxx");'        # no longer works
> perl -e 'system ("(/bin/ls -l /tmp>");'                 # no longer works
>
> Perl's system() function is just the Unix system() call.  The string
> argument is a command line to execute.  The same commands work in a shell
> script (/bin/sh, /bin/csh, and /bin/bash).

You miss the important distinction: system indirectly via sh or
directly without.
  perldoc -f system
With a string argument without certain shell-redirections or with list
it calls execve directly.
"/bin/ls -l /tmp > /tmp/xxx" uses an intermediate sh call to execute,
and this fails with an
out of memory = rebase problem.

> This is a sudden change of behavior we are seeing on our machines.  We have
> several XP machines, some with old Cygwin installations and some with brand
> new ones.  So I would hazard a guess that it is not due to any change in
> Cygwin.

rebaseall

> Here is a log of what happens.  The call never seems to terminate.  I've
> waited up to 15 minutes.  ^C does not work.  ^Z fortunately does.  The first
> message (couldn't allocate) comes out after perhaps 15 seconds.  The second
> message (wait failed) takes minutes to appear.
>
> ------------------------------------------------------------------------------
> xp-1: perl -e ' system ( "/bin/ls -l /tmp" ); '
> total 5
> -r-xr-x---+ 1 geb Users 2222 2007-10-15 18:37 XWin.log
> -r-xr-x---+ 1 geb Users    0 2007-11-27 18:16 sh-thd-1196200453
> -rw-rw-r--+ 1 geb None   177 2012-01-27 12:50 xxx
> xp-2: perl -e ' system ( "/bin/ls -l /tmp > /tmp/xxx" ); '
>     22 [main] sh 5216 C:\cygwin\bin\sh.exe: *** fatal error - couldn't allocate heap, Win32 error 487, base 0x970000, top 0x9B0000, reserve_size 258048, allocsize 262144, page_const 4096
>     33 [main] sh 4312 child_info::sync: wait failed, pid 5216, Win32 error 0
>    335 [main] sh 4312 fork: child -1 - died waiting for longjmp before initialization, retry 0, exit code 0x1000000, errno 11
>     22 [main] sh 4696 C:\cygwin\bin\sh.exe: *** fatal error - couldn't allocate heap, Win32 error 487, base 0x970000, top 0x9B0000, reserve_size 258048, allocsize 262144, page_const 4096
> 311004651 [main] sh 4312 child_info::sync: wait failed, pid 4696, Win32 error 0
> 311004816 [main] sh 4312 fork: child -1 - died waiting for longjmp before initialization, retry 0, exit code 0x1000000, errno 11
>     22 [main] sh 4700 C:\cygwin\bin\sh.exe: *** fatal error - couldn't allocate heap, Win32 error 487, base 0x970000, top 0x9B0000, reserve_size 258048, allocsize 262144, page_const 4096
> ^Z
-- 
Reini Urban
http://cpanel.net/   http://www.perl-compiler.org/

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