Re: [bug #53201] Target runs incorrect command when shebang line exceeds kernel limit

[Brian Vandenberg]

  I cannot remark on pip specifically, but some script interpreters seem to ignore the shebang line if the script is passed as an argument:

$ cat /tmp/blah.sh

#!/bin/bash

printf( "%s:%d\n", __FILE__, __LINE__ );

$ /tmp/blah.sh

/tmp/blah.sh: line 2: syntax error near unexpected token `"%s:%d\n",'

/tmp/blah.sh: line 2: `printf( "%s:%d\n", __FILE__, __LINE__ );'

$ perl /tmp/blah.sh

/tmp/blah.sh: line 2: syntax error near unexpected token `"%s:%d\n",'

/tmp/blah.sh: line 2: `printf( "%s:%d\n", __FILE__, __LINE__ );'

From the above it's apparent that perl (without extra args) obeys the shebang line; ditto for ruby (example omitted).  This next example demonstrates that bash (versions 3.2 and 4.3.33) does not:

$ cat /tmp/stuff.sh

#!/usr/bin/perl

printf( "%s:%d\n", __FILE__, __LINE__ );

$ /tmp/stuff.sh

/tmp/stuff.sh:2

$ bash /tmp/stuff.sh
/tmp/stuff.sh: line 2: syntax error near unexpected token `"%s:%d\n",'

/tmp/stuff.sh: line 2: `printf( "%s:%d\n", __FILE__, __LINE__ );'

I've omitted the text, but I ran the same test with sh, csh, tcsh, zsh and python.

In summary, when the script is passed as an argument to interpreter:

obeyed shebang: perl, ruby

ignored shebang: sh, csh, tcsh, zsh, bash, python

-brian

On Thu, Feb 22, 2018 at 6:16 AM, David Boyce <address@hidden> wrote:

On Thu, Feb 22, 2018 at 4:42 AM, <address@hidden> wrote:

Casey McGinty writes:
 > Follow-up Comment #2, bug #53201 (project make):
 >
 > See http://man7.org/linux/man-pages/man2/execve.2.html
 >
 > *A maximum line length of 127 characters is allowed for the first line in an
 > interpreter script.*

 I think this is referring to the '#!' line of a script, not internal
 kernel limits.  This limitation should not affect Gnu Make recipes.

Well, the #! limit is a kernel limit too. But your point that it shouldn't affect GNU make recipes (directly) is a good one since make invokes recipes via "/bin/sh -c recipe" without ever using a shebang. I have to admit I'm a little lost on where the shebang limit is coming in here but it does seem to be somehow.

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