[gentoo-user] search patterns in less(1)

[gentoo-user] search patterns in less(1)

[n952162]

in less(1), how do you search for a pattern at the beginning (or ending)
of a word.

Elsewhere, you prepend (or append) the pattern with \< (\>) but that's
not working for me with gentoo.

Also, where the change is  documented.

Re: [gentoo-user] search patterns in less(1)

[Michael Orlitzky]

On 7/18/19 6:40 PM, n952162 wrote:
> in less(1), how do you search for a pattern at the beginning (or ending)
> of a word.
> 

Hit front slash "/" in less, and then type a perl-compatible regular
expression. Specifically, try

https://www.pcre.org/original/doc/html/pcrepattern.html#smallassertions


> 
> Also, where the change is  documented.
> 

man less

Re: [gentoo-user] search patterns in less(1)

[n952162]

The man page says:

   The pattern is a regular expression, as recognized by
               the regular expression library supplied by  your system

There are many regular expression libraries on my system.

Anyway, thank you for the (unexpected) tip:

   man perlre

That says to use \b instead of the decades-old \<.


On 07/18/19 20:55, Michael Orlitzky wrote:
> On 7/18/19 6:40 PM, n952162 wrote:
>> in less(1), how do you search for a pattern at the beginning (or ending)
>> of a word.
>>
> Hit front slash "/" in less, and then type a perl-compatible regular
> expression. Specifically, try
>
> https://www.pcre.org/original/doc/html/pcrepattern.html#smallassertions
>
>
>> Also, where the change is  documented.
>>
> man less
>

Re: [gentoo-user] search patterns in less(1)

[Michael Orlitzky]

On 7/19/19 2:40 AM, n952162 wrote:
> The man page says:
> 
>    The pattern is a regular expression, as recognized by
>                the regular expression library supplied by  your system
> 
> There are many regular expression libraries on my system.
> 

You caught me, I did

  $ ldd /usr/bin/less
	linux-vdso.so.1 (0x00007fffb1ea9000)
	libncursesw.so.6 => /lib64/libncursesw.so.6 (0x00007fce26a12000)
	libpcre.so.1 => /lib64/libpcre.so.1 (0x00007fce269cc000)
	libc.so.6 => /lib64/libc.so.6 (0x00007fce267fc000)
	/lib64/ld-linux-x86-64.so.2 (0x00007fce26ae5000)

and saw libpcre in there.

Re: [gentoo-user] search patterns in less(1)

[Michael Orlitzky]

On 7/19/19 11:28 AM, Michael Orlitzky wrote:
> On 7/19/19 2:40 AM, n952162 wrote:
>> The man page says:
>>
>>    The pattern is a regular expression, as recognized by
>>                the regular expression library supplied by  your system
>>
>> There are many regular expression libraries on my system.
>>
> 

Actually, the ambiguity in the man page is there for a reason. When you
configure less, you can pass --with-regex=<library> to select an
implementation. You get libpcre with USE=pcre in Gentoo. Without
USE=pcre, I think you get the GNU libc implementation (from grep et al.)
that just coincidentally supports "\b" as well.

There are a few other options for that flag that aren't available in
Gentoo, though, so the man page is being vague out of necessity.

[gentoo-user] Re: search patterns in less(1)

[Ian Zimmerman]

On 2019-07-19 06:40, n952162 wrote:

> Anyway, thank you for the (unexpected) tip:
> 
> man perlre
> 
> That says to use \b instead of the decades-old \<.

I did not expect it either, but I convinced myself running

  ldd `which less`

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