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my learnings and observations of awk

== intro ==

i'm making notes as i audit the awk workshop[1] (run by the 
author of bottles[2]).

== which awk ==

it looks like on sdf[3] we've all the awks (except the one true 
awk, although I could be wrong). i think we're using nawk because 
they have the same version number and usage messages.

on my pi (bookworm) i've got nawk and mawk.

for demonstration purposes i'm probably going to stick to nawk
compatibility.

== basics ==

note: this is mostly cribbed from the pcom chat for day 1[4]

- each line is a record
- fields in a line are separated by whitespace (including tabs)
- code structure (blocks): BEGIN{}, body + functions, END{}
- BEGIN{} - initialisation (variables)
- {} (body) - aggregation
- END{} - summary
- scripts can be referenced using `-f` switch and you can keep 
the blocks in separate scripts
- variables get declared using the '-v' switch (see examples) or
declare them in the BEGIN{} block
- all maths operations are floats
- uninitialised variables automagically set to 0 for maths

== data transfer (piping, redirection) ==

```
# both of these examples have the same behaviour
echo 'hello' | awk '//' # // match everything, no filtering
awk '//' world.txt # assuming world.txt contains 'hello'
```

== examples

```
# assigning a variable and using command substitution
$echo 'AWKward..' \
	| awk -vMoo='cowsay' '{print |Moo}END{close(Moo)}'

 ___________
< AWKward.. >
 -----------
        \   ^__^
         \  (oo)\_______
            (__)\       )\/\
                ||----w |
                ||     ||

# note: you could have used BEGIN{Moo="cowsay"} to avoid using
# the '-v' switch

# awk as a shebang
#! /usr/bin/awk -f
BEGIN { print "hello, world" }

# shell wrapper script
#! /bin/sh -
AWKCODE='BEGIN { print "hello, world" }'
awk "$AWKCODE"

# using body and END{} blocks to count lines
seq 0 9 | awk '{Lines = Lines + 1} END{print "Lines = ", Lines}'
Lines = 10

# now to sum up numbers
seq 0 9 | awk '{Sum = Sum + $1} END{print "Sum = ", Sum}'
Sum = 45


== references ==


== holding pen ==

links and notes that i haven't referenced in this text file

https://rawtext.club/~woog/misc/awk_workshop.html
https://git.luxferre.top/awk-gold-collection/log.html

== links ==

[1]: gopher://sdf.org:70/1/users/bottles/awk_workshop/
[2]: gopher://gopher.club:70/1/users/bottles/forum/
[3]: gopher://sdf.org:70/1/sdf/faq/
[4]: gopher://sdf.org:70/0/users/bottles/awk_workshop/Day1.log