Re: Dash quoting bug?

Re: Dash quoting bug?

[Herbert Xu]

On Thu, Nov 29, 2007 at 08:32:55AM -0500, Eric Sunshine wrote:
>
> According to the dash manual, within single quotes, all characters are 
> treated as literals (except single quote), which appears to agree with 
> POSIX, so the above behavior seems incorrect.

We need a patch for the dash manual :)

Unfortunately according to POSIX we must interpret these escape sequences:

12680 NAME
12681            echo - write arguments to standard output

12682 SYNOPSIS
12683            echo [string ...]

12684 DESCRIPTION
12685            The echo utility writes its arguments to standard output, followed by a <newline>. If there are
12686            no arguments, only the <newline> is written.

12687 OPTIONS
12688            The echo utility shall not recognize the "- -" argument in the manner specified by Guideline 10
12689            of the Base Definitions volume of IEEE Std 1003.1-200x, Section 12.2, Utility Syntax Guidelines;
12690            "- -" shall be recognized as a string operand.
12691            Implementations shall not support any options.

12692 OPERANDS
12693            The following operands shall be supported:
12694            string       A string to be written to standard output. If any operand is -n, it shall be treated as
12695                         a string, not an option. The following character sequences shall be recognized
12696                         within any of the arguments:
12697                         \a        Write an <alert>.
12698                         \b        Write a <backspace>.
12699                         \c        Suppress the <newline> that otherwise follows the final argument in the
12700                                   output. All characters following the '\c' in the arguments shall be
12701                                   ignored.
12702                         \f        Write a <form-feed>.
12703                         \n        Write a <newline>.
12704                         \r        Write a <carriage-return>.
12705                         \t        Write a <tab>.
12706                         \v        Write a <vertical-tab>.
12707                         \\        Write a backslash character.
12708                         \0num Write an 8-bit value that is the zero, one, two, or three-digit octal number
12709                                   num.

I suggest that you switch over printf for portability.  That is, replace
all occurances of

	echo "string"

with

	printf "%s\n" "string

Cheers,
-- 
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Email: Herbert Xu ~{PmV>HI~} <herbert@gondor.apana.org.au>
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Re: Dash quoting bug?

[Eric Sunshine]

Herbert Xu wrote:
> On Thu, Nov 29, 2007 at 08:32:55AM -0500, Eric Sunshine wrote:
>> According to the dash manual, within single quotes, all characters are 
>> treated as literals (except single quote), which appears to agree with 
>> POSIX, so the above behavior seems incorrect.
> We need a patch for the dash manual :)
> Unfortunately according to POSIX we must interpret these escape sequences:
> 12682 SYNOPSIS
> 12683   echo [string ...]
> 12695     The following character sequences shall be recognized
> 12696     within any of the arguments:
> 12703       \n        Write a <newline>.

Thank you for the response and for pointing out this documentation.

> I suggest that you switch over printf for portability.  That is,
> replace all occurances of
> 	echo "string"
> with
> 	printf "%s\n" "string

Unfortunately, in this case, a portability requirement to older 
platforms lacking 'printf' negates the viability of such a solution. As 
it turns out, however, I was able to resolve the issue by eliminating 
the need to emit backslashes, thus altogether side-stepping the problem.

-- ES