[PATCH] \e in "echo" and "printf" builtins

[PATCH] \e in "echo" and "printf" builtins

[Adam Borowski]

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Hi!

I'm not sure what's your policy towards extensions, but \e as \033 is
something ubiquitous in the Unix world.  C compilers (gcc, clang, icc and
tcc -- but not MSVC), perl, shells (bash and zsh -- but not dash), etc.

What about supporting it in dash as well?
Patch attached.

-- 
Gnome 3, Windows 8, Slashdot Beta, now Firefox Ribbon^WAustralis.  WTF is going
on with replacing usable interfaces with tabletized ones?

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From a6e6e7b6f3a725b4ca0514f22e9ee4cfe2c225e2 Mon Sep 17 00:00:00 2001
From: Adam Borowski <kilobyte@angband.pl>
Date: Sat, 28 Jun 2014 06:29:56 +0200
Subject: [PATCH] Support \e in "echo" and "printf" builtins.

Signed-off-by: Adam Borowski <kilobyte@angband.pl>
---
 src/bltin/printf.c | 1 +
 src/dash.1         | 4 ++++
 2 files changed, 5 insertions(+)

diff --git a/src/bltin/printf.c b/src/bltin/printf.c
index 893295c..98d954c 100644
--- a/src/bltin/printf.c
+++ b/src/bltin/printf.c
@@ -300,6 +300,7 @@ conv_escape(char *str, int *conv_ch)
 	case '\\':	value = '\\';	break;	/* backslash */
 	case 'a':	value = '\a';	break;	/* alert */
 	case 'b':	value = '\b';	break;	/* backspace */
+	case 'e':	value = '\e';	break;  /* escape */
 	case 'f':	value = '\f';	break;	/* form-feed */
 	case 'n':	value = '\n';	break;	/* newline */
 	case 'r':	value = '\r';	break;	/* carriage-return */
diff --git a/src/dash.1 b/src/dash.1
index 3847d98..7107faa 100644
--- a/src/dash.1
+++ b/src/dash.1
@@ -1199,6 +1199,8 @@ Subsequent output is suppressed.  This is normally used at the end of the
 last argument to suppress the trailing newline that
 .Ic echo
 would otherwise output.
+.It Li \ee
+Outputs an escape character (ESC).
 .It Li \ef
 Output a form feed.
 .It Li \en
@@ -1573,6 +1575,8 @@ The characters and their meanings are as follows:
 Write a \*[Lt]bell\*[Gt] character.
 .It Cm \eb
 Write a \*[Lt]backspace\*[Gt] character.
+.It Cm \ee
+Write an \*[Lt]escape\*[Gt] (ESC) character.
 .It Cm \ef
 Write a \*[Lt]form-feed\*[Gt] character.
 .It Cm \en
-- 
2.0.0

Re: [PATCH] \e in "echo" and "printf" builtins

[Harald van Dijk]

On 28/06/14 06:56, Adam Borowski wrote:
> Hi!
> 
> I'm not sure what's your policy towards extensions, but \e as \033 is
> something ubiquitous in the Unix world.  C compilers (gcc, clang, icc and
> tcc -- but not MSVC), perl, shells (bash and zsh -- but not dash), etc.
> 
> What about supporting it in dash as well?
> Patch attached.

Hi,

No comment on whether dash itself should accept \e, but you already
found a compiler that doesn't support it at all, and many of the ones
that do support it also (optionally) issue a warning for it. Should the
C code perhaps be using \033 instead of \e?

Cheers,
Harald van Dijk

Re: [PATCH] \e in "echo" and "printf" builtins

[Adam Borowski]

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On Sat, Jun 28, 2014 at 06:52:51PM +0200, Harald van Dijk wrote:
> On 28/06/14 06:56, Adam Borowski wrote:
> > I'm not sure what's your policy towards extensions, but \e as \033 is
> > something ubiquitous in the Unix world.  C compilers (gcc, clang, icc and
> > tcc -- but not MSVC), perl, shells (bash and zsh -- but not dash), etc.
> 
> No comment on whether dash itself should accept \e, but you already
> found a compiler that doesn't support it at all, and many of the ones
> that do support it also (optionally) issue a warning for it. Should the
> C code perhaps be using \033 instead of \e?

I don't think anyone is going to ever port dash to MSVC, but you have a
point: some other new compiler can appear.

A version of the patch with \033 attached.

-- 
Gnome 3, Windows 8, Slashdot Beta, now Firefox Ribbon^WAustralis.  WTF is going
on with replacing usable interfaces with tabletized ones?

[-- Attachment #2: 0001-Support-e-in-echo-and-printf-builtins.patch --]
[-- Type: text/x-diff, Size: 1568 bytes --]

From a6e6e7b6f3a725b4ca0514f22e9ee4cfe2c225e2 Mon Sep 17 00:00:00 2001
From: Adam Borowski <kilobyte@angband.pl>
Date: Sat, 28 Jun 2014 06:29:56 +0200
Subject: [PATCH] Support \e in "echo" and "printf" builtins.

Signed-off-by: Adam Borowski <kilobyte@angband.pl>
---
 src/bltin/printf.c | 1 +
 src/dash.1         | 4 ++++
 2 files changed, 5 insertions(+)

diff --git a/src/bltin/printf.c b/src/bltin/printf.c
index 893295c..98d954c 100644
--- a/src/bltin/printf.c
+++ b/src/bltin/printf.c
@@ -300,6 +300,7 @@ conv_escape(char *str, int *conv_ch)
 	case '\\':	value = '\\';	break;	/* backslash */
 	case 'a':	value = '\a';	break;	/* alert */
 	case 'b':	value = '\b';	break;	/* backspace */
+	case 'e':	value = '\033';	break;  /* escape */
 	case 'f':	value = '\f';	break;	/* form-feed */
 	case 'n':	value = '\n';	break;	/* newline */
 	case 'r':	value = '\r';	break;	/* carriage-return */
diff --git a/src/dash.1 b/src/dash.1
index 3847d98..7107faa 100644
--- a/src/dash.1
+++ b/src/dash.1
@@ -1199,6 +1199,8 @@ Subsequent output is suppressed.  This is normally used at the end of the
 last argument to suppress the trailing newline that
 .Ic echo
 would otherwise output.
+.It Li \ee
+Outputs an escape character (ESC).
 .It Li \ef
 Output a form feed.
 .It Li \en
@@ -1573,6 +1575,8 @@ The characters and their meanings are as follows:
 Write a \*[Lt]bell\*[Gt] character.
 .It Cm \eb
 Write a \*[Lt]backspace\*[Gt] character.
+.It Cm \ee
+Write an \*[Lt]escape\*[Gt] (ESC) character.
 .It Cm \ef
 Write a \*[Lt]form-feed\*[Gt] character.
 .It Cm \en
-- 
2.0.0

Re: [PATCH] \e in "echo" and "printf" builtins

[Adam Borowski]

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On Sat, Jun 28, 2014 at 07:27:22PM +0200, Adam Borowski wrote:
> On Sat, Jun 28, 2014 at 06:52:51PM +0200, Harald van Dijk wrote:
> > On 28/06/14 06:56, Adam Borowski wrote:
> > > I'm not sure what's your policy towards extensions, but \e as \033 is
> > > something ubiquitous in the Unix world.  C compilers (gcc, clang, icc and
> > > tcc -- but not MSVC), perl, shells (bash and zsh -- but not dash), etc.
> > 
> > No comment on whether dash itself should accept \e, but [...]

So... can I has an answer whether dash should indeed accept \e ?
Being told "no" or "go away, we hate you" is fine, I just dislike having
patches rot forever.  And not having this shorthand is annoying if you
like using colour for highlights -- it works in perl and bash, then
suddenly Oops! not in /bin/sh = dash.


Meow!
-- 
// If you believe in so-called "intellectual property", please immediately
// cease using counterfeit alphabets.  Instead, contact the nearest temple
// of Amon, whose priests will provide you with scribal services for all
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From a6e6e7b6f3a725b4ca0514f22e9ee4cfe2c225e2 Mon Sep 17 00:00:00 2001
From: Adam Borowski <kilobyte@angband.pl>
Date: Sat, 28 Jun 2014 06:29:56 +0200
Subject: [PATCH] Support \e in "echo" and "printf" builtins.

Signed-off-by: Adam Borowski <kilobyte@angband.pl>
---
 src/bltin/printf.c | 1 +
 src/dash.1         | 4 ++++
 2 files changed, 5 insertions(+)

diff --git a/src/bltin/printf.c b/src/bltin/printf.c
index 893295c..98d954c 100644
--- a/src/bltin/printf.c
+++ b/src/bltin/printf.c
@@ -300,6 +300,7 @@ conv_escape(char *str, int *conv_ch)
 	case '\\':	value = '\\';	break;	/* backslash */
 	case 'a':	value = '\a';	break;	/* alert */
 	case 'b':	value = '\b';	break;	/* backspace */
+	case 'e':	value = '\033';	break;  /* escape */
 	case 'f':	value = '\f';	break;	/* form-feed */
 	case 'n':	value = '\n';	break;	/* newline */
 	case 'r':	value = '\r';	break;	/* carriage-return */
diff --git a/src/dash.1 b/src/dash.1
index 3847d98..7107faa 100644
--- a/src/dash.1
+++ b/src/dash.1
@@ -1199,6 +1199,8 @@ Subsequent output is suppressed.  This is normally used at the end of the
 last argument to suppress the trailing newline that
 .Ic echo
 would otherwise output.
+.It Li \ee
+Outputs an escape character (ESC).
 .It Li \ef
 Output a form feed.
 .It Li \en
@@ -1573,6 +1575,8 @@ The characters and their meanings are as follows:
 Write a \*[Lt]bell\*[Gt] character.
 .It Cm \eb
 Write a \*[Lt]backspace\*[Gt] character.
+.It Cm \ee
+Write an \*[Lt]escape\*[Gt] (ESC) character.
 .It Cm \ef
 Write a \*[Lt]form-feed\*[Gt] character.
 .It Cm \en
-- 
2.0.0

Re: [PATCH] \e in "echo" and "printf" builtins

[Jérémie Courrèges-Anglas]

Adam Borowski <kilobyte@angband.pl> writes:

> On Sat, Jun 28, 2014 at 07:27:22PM +0200, Adam Borowski wrote:
>> On Sat, Jun 28, 2014 at 06:52:51PM +0200, Harald van Dijk wrote:
>> > On 28/06/14 06:56, Adam Borowski wrote:
>> > > I'm not sure what's your policy towards extensions, but \e as \033 is
>> > > something ubiquitous in the Unix world.  C compilers (gcc, clang, icc and
>> > > tcc -- but not MSVC), perl, shells (bash and zsh -- but not dash), etc.
>> > 
>> > No comment on whether dash itself should accept \e, but [...]
>
> So... can I has an answer whether dash should indeed accept \e ?
> Being told "no" or "go away, we hate you" is fine, I just dislike having
> patches rot forever.  And not having this shorthand is annoying if you
> like using colour for highlights -- it works in perl and bash, then
> suddenly Oops! not in /bin/sh = dash.

I agree with Erik Blake, IMO there is no reason for dash to support \e
unless POSIX standardizes it first.  Except if you want to encourage
unportable scripts, of course.  /bin/sh is not necessarily bash or dash.

$ /bin/sh
$ type echo
echo is a shell builtin
$ echo '\033[1m hello \033[0m'
 hello # (bold)
$ /bin/echo '\033[1m hello \033[0m'
\033[1m hello \033[0m
$ echo '\e[1m hello \e[0m'
\e[1m hello \e[0m
$ /bin/echo  '\e[1m hello \e[0m'
\e[1m hello \e[0m
$

-- 
jca | PGP : 0x1524E7EE / 5135 92C1 AD36 5293 2BDF  DDCC 0DFA 74AE 1524 E7EE

Re: [PATCH] \e in "echo" and "printf" builtins

[Paul Gilmartin]

On 2014-06-28, at 10:52, Harald van Dijk wrote:

> On 28/06/14 06:56, Adam Borowski wrote:
>> 
>> 
>> I'm not sure what's your policy towards extensions, but \e as \033 is
>> something ubiquitous in the Unix world.  C compilers (gcc, clang, icc and
>> tcc -- but not MSVC), perl, shells (bash and zsh -- but not dash), etc.
>> 
>> What about supporting it in dash as well?
>> 
As a mostly passive lurker, I'm inclined to say, "No.  Dash doesn't
want to become bash."

   http://windtoons.com/images/Camel_-Head-Under-Tent-large.gif

OTOH, there's a POSIX requirement that builtins be indistinguishable
(except in performance) from the corresponding executables. 


> No comment on whether dash itself should accept \e, but you already
> found a compiler that doesn't support it at all, and many of the ones
> that do support it also (optionally) issue a warning for it. Should the
> C code perhaps be using \033 instead of \e?
> 
And here I put on my EBCDIC hat (crown of thorns) and say, "Be careful
using numeric code points; they're not portable."

-- gil

Re: [PATCH] \e in "echo" and "printf" builtins

[Harald van Dijk]

On 28/06/14 19:33, Paul Gilmartin wrote:
> On 2014-06-28, at 10:52, Harald van Dijk wrote:
>> No comment on whether dash itself should accept \e, but you already
>> found a compiler that doesn't support it at all, and many of the ones
>> that do support it also (optionally) issue a warning for it. Should the
>> C code perhaps be using \033 instead of \e?
>>
> And here I put on my EBCDIC hat (crown of thorns) and say, "Be careful
> using numeric code points; they're not portable."

The way GCC does this is to hard-code the values for ASCII, and to
hard-code the values for EBCDIC, both hidden behind preprocessor macros.
Taking that approach in dash would look something like

#if defined(ASCII)
#define ESCAPE '\033'
#elif defined(EBCDIC)
#define ESCAPE '\047'
#else
#error Unknown character set
#endif

and then use ESCAPE.

ASCII and EBCDIC would be detected (or specified) by the configure script.

But dash does have an assumption of ASCII already, which is why I didn't
think it would hurt to add one more. At the very least, it uses
hard-coded \033s in src/hetio.c, so that part of the code already cannot
be used on EBCDIC systems.

Cheers,
Harald van Dijk

Re: [PATCH] \e in "echo" and "printf" builtins

[Eric Blake]

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On 06/28/2014 11:33 AM, Paul Gilmartin wrote:
> 
> OTOH, there's a POSIX requirement that builtins be indistinguishable
> (except in performance) from the corresponding executables. 


The POSIX requirement only applies to portable uses of the builtin - ie.
those that are prescribed by POSIX.  Since POSIX does not require \e,
dash is not failing compliance, even if it differs from extensions
provided by corresponding executables.  I do not think dash needs to
bloat for \e unless POSIX standardizes it first.

-- 
Eric Blake   eblake redhat com    +1-919-301-3266
Libvirt virtualization library http://libvirt.org


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