help for needs to mention for ((...))

[積丹尼 Dan Jacobson]

$ help for
only mentions
   for name [ [ in [ word ... ] ] ; ] do list ; done
and needs to be updated to mention
   for (( expr1 ; expr2 ; expr3 )) ; do list ; done
$ echo $BASH_VERSION
5.1.8(1)-release

Re: help for needs to mention for ((...))

[Lawrence Velázquez]

On Sun, Sep 19, 2021, at 3:25 PM, 積丹尼 Dan Jacobson wrote:
> $ help for
> only mentions
>for name [ [ in [ word ... ] ] ; ] do list ; done
> and needs to be updated to mention
>for (( expr1 ; expr2 ; expr3 )) ; do list ; done

Not particularly intuitive, but:

bash-5.1$ help 'for (('
for ((: for (( exp1; exp2; exp3 )); do COMMANDS; done
Arithmetic for loop.

Equivalent to
(( EXP1 ))
while (( EXP2 )); do
COMMANDS
(( EXP3 ))
done
EXP1, EXP2, and EXP3 are arithmetic expressions.  If any expression is
omitted, it behaves as if it evaluates to 1.

Exit Status:
Returns the status of the last command executed.

-- 
vq

Re: help for needs to mention for ((...))

[Dennis Williamson]

On Sun, Sep 19, 2021, 4:07 PM Lawrence Velázquez  wrote:

> On Sun, Sep 19, 2021, at 3:25 PM, 積丹尼 Dan Jacobson wrote:
> > $ help for
> > only mentions
> >for name [ [ in [ word ... ] ] ; ] do list ; done
> > and needs to be updated to mention
> >for (( expr1 ; expr2 ; expr3 )) ; do list ; done
>
> Not particularly intuitive, but:
>
> bash-5.1$ help 'for (('
> for ((: for (( exp1; exp2; exp3 )); do COMMANDS; done
> Arithmetic for loop.
>
> Equivalent to
> (( EXP1 ))
> while (( EXP2 )); do
> COMMANDS
> (( EXP3 ))
> done
> EXP1, EXP2, and EXP3 are arithmetic expressions.  If any expression is
> omitted, it behaves as if it evaluates to 1.
>
> Exit Status:
> Returns the status of the last command executed.
>
> --
> vq
>


And

help 'for*'

(No space) gets them both.

>

Re: help for needs to mention for ((...))

[積丹尼 Dan Jacobson]

OK, then "help for" should at least mention that trick to get the rest of
the story.

Re: help for needs to mention for ((...))

[積丹尼 Dan Jacobson]

$ help f|wc -l
72
$ help fo   |wc -l
24
$ help for  |wc -l
10
$ help for\ |wc -l
14
$ help for\ \(  |wc -l
14
$ help for\ \(\(|wc -l
14

So help help's 'If PATTERN is specified, gives detailed help on all
commands matching PATTERN." is not telling the whole story about
matching.

Re: help for needs to mention for ((...))

[積丹尼 Dan Jacobson]

OK, so it first looks for exact hits,
then does a grep style match.
And we see that

$ help f|grep :.
false: false
fc: fc [-e ename] [-lnr] [first] [last] or fc -s [pat=rep] [command]
fg: fg [job_spec]
for: for NAME [in WORDS ... ] ; do COMMANDS; done
for ((: for (( exp1; exp2; exp3 )); do COMMANDS; done
function: function name { COMMANDS ; } or name () { COMMANDS ; }

the function name is 'for (('
not 'for (( ))' etc.
Great.