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* help adapting bashism for zsh
@ 2019-06-10  0:33 David C. Rankin
  2019-06-10  5:41 ` Roman Perepelitsa
  2019-06-10 20:22 ` Bart Schaefer
  0 siblings, 2 replies; 9+ messages in thread
From: David C. Rankin @ 2019-06-10  0:33 UTC (permalink / raw)
  To: zsh-users

All,

  There is a lot I like about zsh, but almost an equal amount I don't. The
problem is how to handle adapting the 2566 POSIX and bash scripts I have to be
zsh compatible. The biggest issues are parameter-expansions, 1's indexing, and
issues with 'type' and other builtins being just enough different that my
existing scripts break when using zsh as the interpreter.

  Is there any collection of aliases, tweaks, brute-force sed scripts, etc..
that I could look at an pull parts from to handle most of the issues?

  For example with 'type', I can alias it to 'whence', but the documentation
for it is of little help with the expected behavior for type itself, e.g.

type [ -wfpamsS ] name ...

    Equivalent to whence -v.

at http://zsh.sourceforge.net/Doc/Release/Shell-Builtin-Commands.html, but the
options [ -wfpamsS ] largely have no effect on how type behaves.

  Then what to do with a large portions of the scripts that rely heavily on
string indexing and C-style for loops? The KSH_ARRAYS options is a temporary
bandaid for C-style loops, but that injects zsh incompatibility and the
documentation is absent on its effect on string indexing (e.g.
${foo:offset:length}). Then what to do about the non-existing expansions such
as ${foo^^} (uppercase) and ${foo,,} (lowercase), etc..

  In looking for solutions, I want to stay with core zsh solution, instead of
plugins, modules, etc...

  Is there some collection of information that helps with this transition
process, or is it largely a script-by-script rewrite to make the scripts
compatible?

-- 
David C. Rankin, J.D.,P.E.

^ permalink raw reply	[flat|nested] 9+ messages in thread

* Re: help adapting bashism for zsh
  2019-06-10  0:33 help adapting bashism for zsh David C. Rankin
@ 2019-06-10  5:41 ` Roman Perepelitsa
  2019-06-10 14:43   ` David C. Rankin
  2019-06-10 20:22 ` Bart Schaefer
  1 sibling, 1 reply; 9+ messages in thread
From: Roman Perepelitsa @ 2019-06-10  5:41 UTC (permalink / raw)
  To: David C. Rankin; +Cc: Zsh Users

May I ask why you want to port bash scripts to zsh?

Roman.

^ permalink raw reply	[flat|nested] 9+ messages in thread

* Re: help adapting bashism for zsh
  2019-06-10  5:41 ` Roman Perepelitsa
@ 2019-06-10 14:43   ` David C. Rankin
  2019-06-10 14:53     ` Roman Perepelitsa
  0 siblings, 1 reply; 9+ messages in thread
From: David C. Rankin @ 2019-06-10 14:43 UTC (permalink / raw)
  To: zsh users list

On 06/10/2019 12:41 AM, Roman Perepelitsa wrote:
> May I ask why you want to port bash scripts to zsh?
> 

So when I choose zsh as the only shell installed, things will continue to
work. The easy answer is install all shells, but on storage critical systems
has a distinct downside. That's why I am curious whether there is a collection
of information that can help in the transition.

-- 
David C. Rankin, J.D.,P.E.

^ permalink raw reply	[flat|nested] 9+ messages in thread

* Re: help adapting bashism for zsh
  2019-06-10 14:43   ` David C. Rankin
@ 2019-06-10 14:53     ` Roman Perepelitsa
  2019-06-10 17:34       ` Ray Andrews
  0 siblings, 1 reply; 9+ messages in thread
From: Roman Perepelitsa @ 2019-06-10 14:53 UTC (permalink / raw)
  To: David C. Rankin; +Cc: zsh users list

On Mon, Jun 10, 2019 at 4:44 PM David C. Rankin
<drankinatty@suddenlinkmail.com> wrote:
> So when I choose zsh as the only shell installed, things will continue to
> work. The easy answer is install all shells, but on storage critical systems
> has a distinct downside. That's why I am curious whether there is a collection
> of information that can help in the transition.

On my Linux box sh is 100KB, bash is 1.1MB and zsh is 4.3MB. If you
are space constrained, zsh may not be the best choice.

Going back to your original question, I'm not aware of any tools for
automatic translation of bash code to zsh. It's likely that your
requirements are unique. Usually systems that can afford to have zsh
can also afford to have bash, so no translation is necessary.

Roman.

^ permalink raw reply	[flat|nested] 9+ messages in thread

* Re: help adapting bashism for zsh
  2019-06-10 14:53     ` Roman Perepelitsa
@ 2019-06-10 17:34       ` Ray Andrews
  2019-06-10 21:55         ` David C. Rankin
  0 siblings, 1 reply; 9+ messages in thread
From: Ray Andrews @ 2019-06-10 17:34 UTC (permalink / raw)
  To: zsh-users

On 2019-06-10 7:53 a.m., Roman Perepelitsa wrote:
> automatic translation of bash code to zsh. It's likely that your
> requirements are unique. Usually systems that can afford to have zsh
> can also afford to have bash, so no translation is necessary.
>
In my case I didn't want the bother of having to learn the 
idiosyncrasies of two shells.  I picked one and was hoping to never have 
to learn the other.  If I was planning to transition from bash to zsh, 
I'd be hoping to subsequently avoid bash altogether and thus go through 
the conversion trouble once but then forget about bash and do all 
further work in zsh.  So space considerations would be the least of my 
motives.  Just me, but zsh syntax is so abstruse that not only learning 
it, but also trying to remember the differences vis a vis bash, would 
seem brain blowing.

So it seems David will have to do it line by line.



^ permalink raw reply	[flat|nested] 9+ messages in thread

* Re: help adapting bashism for zsh
  2019-06-10  0:33 help adapting bashism for zsh David C. Rankin
  2019-06-10  5:41 ` Roman Perepelitsa
@ 2019-06-10 20:22 ` Bart Schaefer
  2019-06-10 22:31   ` David C. Rankin
  1 sibling, 1 reply; 9+ messages in thread
From: Bart Schaefer @ 2019-06-10 20:22 UTC (permalink / raw)
  To: David C. Rankin; +Cc: Zsh Users

On Sun, Jun 9, 2019 at 5:34 PM David C. Rankin
<drankinatty@suddenlinkmail.com> wrote:
>
> Is there any collection of aliases, tweaks, brute-force sed scripts, etc..
> that I could look at an pull parts from to handle most of the issues?

First thing -- how are these scripts executed?  E.g., are they run as
standalone processes via interpreter named in a "#!" line at the top,
or are they somehow pulled into an interactive shell, or something
else?

If using the "#!" interpreter, the first thing to try is simply to
symlink that name to your zsh binary.  When invoked as (a path ending
in) "bash" or "sh" (or "ksh"), zsh enters a compatibility mode that
will resolve the most common issues.  You can then work on specific
problems with any scripts that are still failing.

This compatibility mode differs from setting individual options such
as KSH_ARRAYS, but can be fairly closely duplicated by using the
"emulate" command.  If the scripts are intended to become the bodies
of shell functions, try adding "emulate -L sh" at the top.

> Then what to do about the non-existing expansions such
> as ${foo^^} (uppercase) and ${foo,,} (lowercase), etc..

These are handled with (in those specific examples) ${foo:u} and
${foo:l}.  In fact ^^ has a completely different meaning in zsh, so
you will have to do a search-and-replace for those kinds of
nonstandard tricks.

^ permalink raw reply	[flat|nested] 9+ messages in thread

* Re: help adapting bashism for zsh
  2019-06-10 17:34       ` Ray Andrews
@ 2019-06-10 21:55         ` David C. Rankin
  0 siblings, 0 replies; 9+ messages in thread
From: David C. Rankin @ 2019-06-10 21:55 UTC (permalink / raw)
  To: zsh users list

On 06/10/2019 12:34 PM, Ray Andrews wrote:
> On 2019-06-10 7:53 a.m., Roman Perepelitsa wrote:
>> automatic translation of bash code to zsh. It's likely that your
>> requirements are unique. Usually systems that can afford to have zsh
>> can also afford to have bash, so no translation is necessary.
>>
> In my case I didn't want the bother of having to learn the idiosyncrasies of
> two shells.  I picked one and was hoping to never have to learn the other.  If
> I was planning to transition from bash to zsh, I'd be hoping to subsequently
> avoid bash altogether and thus go through the conversion trouble once but then
> forget about bash and do all further work in zsh.  So space considerations
> would be the least of my motives.  Just me, but zsh syntax is so abstruse that
> not only learning it, but also trying to remember the differences vis a vis
> bash, would seem brain blowing.
> 
> So it seems David will have to do it line by line.

  That's the interesting part. I have 2-decades of bash, which with the
bashisms makes that somewhat of a daunting challenge. The "2566 POSIX and bash
scripts" wasn't a guess, it was a 'find ~/scr -type f | wc -l' exercise. From
the days of loading Linux from floppy disks from boxed sets, you didn't really
have a lot of foresight as to the implications of shell choice, which is what
makes the shell differences now more acute.

  So the path forward seems like leaving all shells installed the only
solution and migrate the needed scripts one at a time. We shall see how it goes.

-- 
David C. Rankin, J.D.,P.E.

^ permalink raw reply	[flat|nested] 9+ messages in thread

* Re: help adapting bashism for zsh
  2019-06-10 20:22 ` Bart Schaefer
@ 2019-06-10 22:31   ` David C. Rankin
  2019-06-11  8:56     ` Peter Stephenson
  0 siblings, 1 reply; 9+ messages in thread
From: David C. Rankin @ 2019-06-10 22:31 UTC (permalink / raw)
  To: zsh users list

On 06/10/2019 03:22 PM, Bart Schaefer wrote:
> This compatibility mode differs from setting individual options such
> as KSH_ARRAYS, but can be fairly closely duplicated by using the
> "emulate" command.  If the scripts are intended to become the bodies
> of shell functions, try adding "emulate -L sh" at the top.
> 
>> Then what to do about the non-existing expansions such
>> as ${foo^^} (uppercase) and ${foo,,} (lowercase), etc..
> These are handled with (in those specific examples) ${foo:u} and
> ${foo:l}.  In fact ^^ has a completely different meaning in zsh, so
> you will have to do a search-and-replace for those kinds of
> nonstandard tricks.

Thank you Bart,

  That seems like the logical path forward. I was sure hoping somebody already
had a handy-dandy parse & convert routine, but it looks like a normal convert
as you go. As I go through them I'll try and keep a list of the most common
bash/zsh conversions and notes of those cases where there is no 1-for-1
replacement. It will be an as-time-permits endeavour, but maybe we can catch
most issues.

-- 
David C. Rankin, J.D.,P.E.

^ permalink raw reply	[flat|nested] 9+ messages in thread

* Re: help adapting bashism for zsh
  2019-06-10 22:31   ` David C. Rankin
@ 2019-06-11  8:56     ` Peter Stephenson
  0 siblings, 0 replies; 9+ messages in thread
From: Peter Stephenson @ 2019-06-11  8:56 UTC (permalink / raw)
  To: zsh-users

On Mon, 2019-06-10 at 17:31 -0500, David C. Rankin wrote:
> On 06/10/2019 03:22 PM, Bart Schaefer wrote:
> > This compatibility mode differs from setting individual options such
> > as KSH_ARRAYS, but can be fairly closely duplicated by using the
> > "emulate" command.  If the scripts are intended to become the bodies
> > of shell functions, try adding "emulate -L sh" at the top.
>
> > > Then what to do about the non-existing expansions such
> > > as ${foo^^} (uppercase) and ${foo,,} (lowercase), etc..
> > These are handled with (in those specific examples) ${foo:u} and
> > ${foo:l}.  In fact ^^ has a completely different meaning in zsh, so
> > you will have to do a search-and-replace for those kinds of
> > nonstandard tricks.
> Thank you Bart,
> 
>   That seems like the logical path forward. I was sure hoping somebody already
> had a handy-dandy parse & convert routine, but it looks like a normal convert
> as you go. As I go through them I'll try and keep a list of the most common
> bash/zsh conversions and notes of those cases where there is no 1-for-1
> replacement. It will be an as-time-permits endeavour, but maybe we can catch
> most issues.

The FAQ, section 2.1, should help, from the Etc directory of the
distribution or http://zsh.sourceforge.net/FAQ/zshfaq02.html#l10

pws


^ permalink raw reply	[flat|nested] 9+ messages in thread

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Thread overview: 9+ messages (download: mbox.gz / follow: Atom feed)
-- links below jump to the message on this page --
2019-06-10  0:33 help adapting bashism for zsh David C. Rankin
2019-06-10  5:41 ` Roman Perepelitsa
2019-06-10 14:43   ` David C. Rankin
2019-06-10 14:53     ` Roman Perepelitsa
2019-06-10 17:34       ` Ray Andrews
2019-06-10 21:55         ` David C. Rankin
2019-06-10 20:22 ` Bart Schaefer
2019-06-10 22:31   ` David C. Rankin
2019-06-11  8:56     ` Peter Stephenson

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