Prig: the snobbish AWK
Prig is for Processing Records In Go. It's like AWK, but snobbish (Go! static typing!). It's also faster to execute, and if you know Go, you don't need to learn AWK.
You can also read my article on why and how I wrote Prig. The tl;dr is "no good reason, I'm a geek!" :-)
How to use Prig
To install prig, make sure Go is installed and then type go install github.com/benhoyt/prig@latest. Prig itself runs the generated code using go build, so even once you have a prig executable it requires the Go compiler to be installed.
As a simple example, you can try the following script. It prints a modified version of the second field of each line of input (the full URL in this example):
$ cat logs.txt
GET /robots.txt HTTP/1.1
HEAD /README.md HTTP/1.1
GET /wp-admin/ HTTP/1.0
$ prig 'Println("https://example.com" + S(2))' <logs.txt
https://example.com/robots.txt
https://example.com/README.md
https://example.com/wp-admin/
To get help, run prig with a -h or --help argument. Help output is copied below, showing more examples at the bottom:
Prig v1.0.0 - Copyright (c) 2022 Ben Hoyt
Usage: prig [options] [-b 'begin code'] 'per-record code' [-e 'end code']
Prig is for Processing Records In Go. It's like AWK, but snobbish (Go! static
typing!). It runs 'begin code' first, then runs 'per-record code' for every
record (line) in the input, then runs 'end code'. Prig uses "go build", so it
requires the Go compiler: https://go.dev/doc/install
Options:
-F char | re field separator (single character or multi-char regex)
-g executable Go compiler to use (eg: "go1.18rc1", default "go")
-h, --help print help message and exit
-i import import Go package (normally automatic)
-s print formatted Go source instead of running
-V, --version print version number and exit
Built-in functions:
F(i int) float64 // return field i as float64, int, or string
I(i int) int // (i==0 is entire record, i==1 is first field)
S(i int) string
NF() int // return number of fields in current record
NR() int // return number of current record
Print(args ...interface{}) // fmt.Print, but buffered
Printf(format string, args ...interface{}) // fmt.Printf, but buffered
Println(args ...interface{}) // fmt.Println, but buffered
Match(re, s string) bool // report whether s contains match of re
Replace(re, s, repl string) string // replace all re matches in s with repl
Submatches(re, s string) []string // return slice of submatches of re in s
Substr(s string, n[, m] int) string // s[n:m] but safe and allow negative n/m
Sort[T int|float64|string](s []T) []T
// return new sorted slice; also Sort(s, Reverse) to sort descending
SortMap[T int|float64|string](m map[string]T) []KV[T]
// return sorted slice of key-value pairs
// also Sort(s[, Reverse][, ByValue]) to sort descending or by value
Examples:
# Run an arbitrary Go snippet; don't process input
prig -b 'Println("Hello, world!", math.Pi)'
# Print the average value of the last field
prig -b 's := 0.0' 's += F(NF())' -e 'Println(s / float64(NR()))'
# Print 3rd field in milliseconds if line contains "GET" or "HEAD"
prig 'if Match(`GET|HEAD`, S(0)) { Printf("%.0fms\n", F(3)*1000) }'
# Print frequencies of unique words, most frequent first
prig -b 'freqs := map[string]int{}' \
'for i := 1; i <= NF(); i++ { freqs[strings.ToLower(S(i))]++ }' \
-e 'for _, f := range SortMap(freqs, ByValue, Reverse) { ' \
-e 'Println(f.K, f.V) }'
Prig uses the golang.org/x/tools/imports package, so imports are usually automatic (use -i if you need to disambiguate, for example between text/template and html/template). And that's really all you need to know -- the code snippets are pure Go.
Other information
If you're looking for a real, POSIX-compatible version of AWK for use in Go programs, see my GoAWK project.
Prig was based on rp, a similar idea for Nim written by Charles Blake.
Prig is licensed under an open source MIT license.
