@kabel42 @rl_dane @amin @sotolf @thedoctor eww, it’s not even a drop-in then…
(For not-a-drop-in, I found pcregrep interesting. Sadly, Debian recently dropped it, but in the versions which don’t have pcregrep any more, you can use grep -P for many use cases. pcre2grep is not a drop-in for pcregrep either…)
@mirabilos @kabel42 @amin @sotolf @thedoctor
I was a total PCRE stan in the olden days, but I've steered more towards regular extended regexp for compatibility. I do miss \d, \w and \s, though. [[:space:]] feels so clumsy to type and use several times in a regex, I'll sometimes put a sp="[[:space:]]" line at the start of a script, and you'll see several invocations of "${sp}" in my regex strings.
But again... compatibility. ;)
Is there a big difference between (GNU) grep -P and pcregrep? I hadn't heard of that utility before.
@amin @kabel42 @rl_dane @sotolf @thedoctor I never used \d and the likes, always felt them much too complicated. I almost never use POSIX character classes (besides the BSD [[:<:]] and [[:>:]]), rather I just hit [ tab space ] quickly.
GNU grep -P does a PCRE grep, it doesn’t support all of the extra flags of pcregrep though, and before the version in IIRC trixie was very broken.
@mirabilos @amin @kabel42 @sotolf @thedoctor
is [[:<:]] and [[:>:]] the same as \< and \>?
@rl_dane @amin @kabel42 @sotolf @thedoctor obviously not, because it’s written differently ;)
re_format(7) knows:
mirabilos
R.L. Dane 
🍵 
There are two special cases** of bracket expressions: the bracket expres-
sions '[[:<:]]' and '[[:>:]]' match the null string at the beginning and
end of a word, respectively. A word is defined as a sequence of charac-
ters starting and ending with a word character which is neither preceded
nor followed by word characters. A word character is an alnum character
(as defined by ctype(3)) or an underscore. This is an extension, compati-
ble with but not specified by POSIX, and should be used with caution in
software intended to be portable to other systems.
(as for the mark:)
POSIX leaves some aspects of RE syntax and semantics open; '**' marks de-
cisions on these aspects that may not be fully portable to other POSIX
implementations.
The definition for \< / \> differs between less, perlre, pcre, … I believe, but they all are somewhat simiar.
@rl_dane @amin @kabel42 @sotolf @thedoctor perlre(1) actually has…
A word boundary ("\b") is a spot between two characters that
has a "\w" on one side of it and a "\W" on the other side of
it (in either order), counting the imaginary characters off
the beginning and end of the string as matching a "\W".
… so the \< probably comes from less(1)?
… hm, no. But, where then?
@mirabilos @amin @kabel42 @sotolf @thedoctor
I used to use \b a lot, but \< and \> are just as easy to use, and POSIX. ;)
\w is nice, though. I think the closest POSIX one is [[:graph:]]? (Not super close, though)
@rl_dane @amin @kabel42 @sotolf @thedoctor \< and \> are not POSIX.
perlre(1) \w is identical to POSIX [a-zA-Z0-9_] in the C locale, so [[:alnum:]_] if you have support for POSIX character classes.
@mirabilos @amin @kabel42 @sotolf @thedoctor
Ah, yes. [[:alnum:]] was the one I was thinking of.
@mirabilos @amin @kabel42 @sotolf @thedoctor
Waiiiiit, what does the underscore before the second bracket do? I've never seen that before.
No mention of it in RE_FORMAT(7) on FreeBSD.
[a-zA-Z0-9_], and I’d be surprised if the FreeBSD manpage would not document it@rl_dane @amin @kabel42 @sotolf @thedoctor let me blow your mind if that was news to you:
[[:alpha:][:digit:]_]
kabel42[ switches from RE context to RE-Bracket context in the bracket-begin state, in which you can have an optional ^ (except in shellglobs where it is spelt !), then an optional ] not taken as the end of the RE-Bracket, then an optional -, then any amount of expressions of the type a-z, [:charclass:], [=equivalenceclass=], x, then an optional -, then a closing ] which terminates the RE-Bracket context.] or the - at the beginning, not both)[a[.ch.]] in e.g. es_ES.UTF-8 matches either a or ch, so a bracket expression in POSIX has a variable matching length…)[[:<:]] and [[:>:]] extension (which matches a zero-length string)@kabel42 @mirabilos @amin @sotolf @thedoctor
Basically spaces and punctuation.
[^char-class] matches “any single character, other than newline, not in char-class”@kabel42 @rl_dane @amin @sotolf @thedoctor yea, I’m just pedantic.
In the RE ^foo[^bar^]baz$ there technically are exactly two carets.
] or - in a bracket expression, and for the newline ofc.@mirabilos @kabel42 @amin @sotolf @thedoctor
Don't you have to backslash escape a right bracket, like [a-z\]]?
[]a-z]@mirabilos @sotolf @thedoctor @amin @kabel42
Ahhhh, good to know. Mentally filed. ;)
@kabel42 @amin @thedoctor @sotolf @rl_dane I often go through logs by first cutting off timestamp
and host using rectangle mode in jupp, then replacing ^([^ ]*)\[[^]]*\]: with \1: and sort -uing.
I’ve also used [][0-9a-fA-F:] to match IP addresses…
@mirabilos @kabel42 @amin @thedoctor @sotolf
I love editors with rectangle selection and editing modes. vim has it, and my first exposure to it was actually in Microsoft Word 4.0 for mac. Obviously not something I use today. XD
@mirabilos @kabel42 @sotolf @thedoctor @amin
Respect to your efforts, but for me, it's modal editing or die. XD
@mirabilos @kabel42 @sotolf @thedoctor @amin
Maybe if I had caps lock mapped to control, rather than escape. ;)
@mirabilos @thedoctor @kabel42 @amin @sotolf
I don't recall seeing anything other than unix terminals and workstations with control to the left of "A"
But yeah, capslock is a dumb key, or at least, that's a dumb placement for it. ;)
@mirabilos @thedoctor @kabel42 @amin @sotolf
Maybe? I'm half a century, roughly. ;)
@mirabilos @thedoctor @kabel42 @amin @sotolf
Ah, yes, that was the very first IBM PC keyboard, the one that didn't have dedicated arrow keys. I never spent much time in front of one (possibly none, not sure), but I was aware of it.
I just didn't realize it had Ctrl in the "correct" position. ^___^
@mirabilos @thedoctor @kabel42 @amin @sotolf
Whoa, there's some seriously unused space on the surface of that keyboard. XD
Someone should have showed them the Amiga 500 ;)
@rl_dane @thedoctor @kabel42 @amin @sotolf huh,
Not much, just the palm rest and where the winkeys are these days.
@rl_dane @thedoctor @kabel42 @amin @sotolf ah but the whole thing is just as high as needed to fit the floppy disc drive.
All the guts are under the keyboard, INCLUDING an ISA slot for extension cards (out of the back at the very left), and all the connectors (HGC/CGA TTL monitor, serial, parallel, power, external HDD connector, external second FDD connector) are also on the back, as is the power button.
sotolf