\e in "echo" and "printf" builtins
PATCH 1/1 \e in "echo" and "printf" builtins
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.
Signature · 2 lines
Gnome 3, Windows 8, Slashdot Beta, now Firefox Ribbon^WAustralis. WTF is going on with replacing usable interfaces with tabletized ones?
From a6e6e7b6f3a725b4ca0514f22e9ee4cfe2c225e2 Mon Sep 17 00:00:00 2001
From: Adam Borowski <[email protected]>
Date: Sat, 28 Jun 2014 06:29:56 +0200
Subject: [PATCH] Support \e in "echo" and "printf" builtins.
--- src/bltin/printf.c | 1 + src/dash.1 | 4 ++++ 2 files changed, 5 insertions(+)
src/bltin/printf.c +1 -0
@@ -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 */
src/dash.1 +4 -0
@@ -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
Signature · 1 line
2.0.0
Quoted 8 lines · Adam Borowski
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
Quoted 9 lines · Harald van Dijk
Quoted 3 lines · Adam Borowski
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.
Signature · 2 lines
Gnome 3, Windows 8, Slashdot Beta, now Firefox Ribbon^WAustralis. WTF is going on with replacing usable interfaces with tabletized ones?
From a6e6e7b6f3a725b4ca0514f22e9ee4cfe2c225e2 Mon Sep 17 00:00:00 2001
From: Adam Borowski <[email protected]>
Date: Sat, 28 Jun 2014 06:29:56 +0200
Subject: [PATCH] Support \e in "echo" and "printf" builtins.
--- src/bltin/printf.c | 1 + src/dash.1 | 4 ++++ 2 files changed, 5 insertions(+)
src/bltin/printf.c +1 -0
@@ -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 */
src/dash.1 +4 -0
@@ -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
Signature · 1 line
2.0.0
Quoted 7 lines · Adam Borowski
Quoted 6 lines · Harald van Dijk
Quoted 3 lines · Adam Borowski
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!
Signature · 4 lines
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From a6e6e7b6f3a725b4ca0514f22e9ee4cfe2c225e2 Mon Sep 17 00:00:00 2001
From: Adam Borowski <[email protected]>
Date: Sat, 28 Jun 2014 06:29:56 +0200
Subject: [PATCH] Support \e in "echo" and "printf" builtins.
--- src/bltin/printf.c | 1 + src/dash.1 | 4 ++++ 2 files changed, 5 insertions(+)
src/bltin/printf.c +1 -0
@@ -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 */
src/dash.1 +4 -0
@@ -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
Signature · 1 line
2.0.0
Quoted 7 lines · Adam Borowski
Quoted 6 lines · Adam Borowski
Quoted 5 lines · Harald van Dijk
Quoted 3 lines · Adam Borowski
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.
Quoted 7 lines
Quoted 1 line
Quoted 1 line
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 $
Signature · 1 line
jca | PGP : 0x1524E7EE / 5135 92C1 AD36 5293 2BDF DDCC 0DFA 74AE 1524 E7EE
Quoted 9 lines · Harald van Dijk
Quoted 8 lines · Adam Borowski
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.
Quoted 5 lines
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
Quoted 8 lines · Paul Gilmartin
Quoted 5 lines · Harald van Dijk
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
Quoted 3 lines · Paul Gilmartin
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.
Signature · 2 lines
Eric Blake eblake redhat com +1-919-301-3266 Libvirt virtualization library http://libvirt.org