Awk and sort (of text files)

[Cameron Simpson]

On 30Jun2015 14:35, Bill Oliver <vendor at billoblog.com> wrote:
>On Mon, 29 Jun 2015, jd1008 wrote:
>
>>[snip]
>>Here is the simplest solution and it does what I want without 
>>resorting to awk:
>>for i in `/bin/ls -1 lists*`; do
>>sed '/./{H;d;};x;s/\n/={NL}=/g' $i | sort | sed 
>>'1s/={NL}=//;s/={NL}=/\n/g' > $i.sorted.txt
>>done
>
>I bow before a Master.
>So, I'm trying to parse this...
>
>I don't know what "NL" does.  From my reading I see the N command adds the 
>current line to the pattern space with a newline character. I can't figure out 
>what the "L" does, though, or if NL is a different command than "N" followed 
>by "L"

The "NL" is not a command. It is simply a piece of text to insert into the line 
in place of newlines. (I'm not sure why - you can certainly hold multiple lines 
in the hold space.)

So the code pulls lines into the hold space and replaces the newline characters 
with the text "NL". Then later it undoes that, replacing the text "NL" with a 
newline character.

Personally I tend to use a nontexty character for this kind of placeholder, 
such as ^G. Less risk of excountering that in the input text, and therefore 
less risk of accidentally mangling it.

Cheers,
Cameron Simpson <cs at zip.com.au>

Don't have awk? Use this simple sh emulation:
    #!/bin/sh
    echo 'Awk bailing out!' >&2
    exit 2
- Tom Horsley <tahorsley at csd.harris.com>