// AWKRS — FULL REFERENCE

# length

length([s])

Length of string s (or $0), or element count of an array.

# substr

substr(s, m [, n])

n-char substring of s starting at position m (1-based).

# index

index(s, t)

1-based position of t in s, or 0 if not found.

# split

split(s, arr [, fs [, seps]])

Split s into arr on fs; returns the field count.

# sub

sub(re, repl [, target])

Replace first match of re in target ($0); returns 1/0.

# gsub

gsub(re, repl [, target])

Replace all matches of re in target ($0); returns count.

# match

match(s, re [, arr])

Set RSTART/RLENGTH to the match of re in s; returns position or 0.

# sprintf

sprintf(fmt, ...)

Format the arguments per fmt and return the string.

# tolower

tolower(s)

Copy of s with uppercase letters lowercased.

# toupper

toupper(s)

Copy of s with lowercase letters uppercased.

# gensub

gensub(re, repl, how [, target])

Non-destructive global/Nth substitution returning the new string.

# sin

sin(x)

Sine of x (radians).

# cos

cos(x)

Cosine of x (radians).

# atan2

atan2(y, x)

Arctangent of y/x in radians.

# exp

exp(x)

e raised to the power x.

# log

log(x)

Natural logarithm of x.

# sqrt

sqrt(x)

Square root of x.

# int

int(x)

Integer part of x, truncated toward zero.

# rand

rand()

Pseudo-random number in [0, 1).

# srand

srand([x])

Seed the RNG with x (or time); returns the previous seed.

# print

print — keyword

Write its arguments to output, separated by OFS and terminated by ORS.

# printf

printf(fmt, ...)

Format and print the arguments per fmt.

# getline

getline — keyword

Read the next record into $0 or a variable from input, a file, or a command.

# close

close(file [, how])

Close an open file/pipe; returns its status.

# system

system(cmd)

Run cmd via the shell; returns its exit status.

# fflush

fflush([file])

Flush buffers for file, or all outputs if omitted.

# systime

systime()

Current time as seconds since the epoch (gawk).

# strftime

strftime([fmt [, ts [, utc]]])

Format timestamp ts per fmt (gawk).

# mktime

mktime(spec [, utc])

Convert a "YYYY MM DD HH MM SS [DST]" spec to a timestamp (gawk).

# and

and(v1, v2, ...)

Bitwise AND of the arguments (gawk).

# or

or(v1, v2, ...)

Bitwise OR of the arguments (gawk).

# xor

xor(v1, v2, ...)

Bitwise XOR of the arguments (gawk).

# compl

compl(v)

Bitwise complement of v (gawk).

# lshift

lshift(v, n)

v left-shifted by n bits (gawk).

# rshift

rshift(v, n)

v right-shifted by n bits (gawk).

# typeof

typeof(x)

Type of x: "scalar", "array", "untyped", … (gawk).

# isarray

isarray(x)

1 if x is an array, else 0 (gawk).

# patsplit

patsplit(s, arr [, fpat [, seps]])

Split s into arr by the pattern fpat (gawk).

# asort

asort(src [, dst [, how]])

Sort array values; returns the element count (gawk).

# asorti

asorti(src [, dst [, how]])

Sort array indices; returns the element count (gawk).

# NR

NR — special variable

Total number of input records read so far.

# NF

NF — special variable

Number of fields in the current record.

# FS

FS — special variable

Input field separator (default " ").

# OFS

OFS — special variable

Output field separator (default " ").

# ORS

ORS — special variable

Output record separator (default "\n").

# RS

RS — special variable

Input record separator (default "\n").

# FILENAME

FILENAME — special variable

Name of the current input file.

# FNR

FNR — special variable

Record number within the current input file.

# RSTART

RSTART — special variable

Start position of the last match() (1-based), or 0.

# RLENGTH

RLENGTH — special variable

Length of the last match(), or -1.

# SUBSEP

SUBSEP — special variable

Subscript separator for multi-dimensional array keys.

# ARGC

ARGC — special variable

Count of command-line arguments in ARGV.

# ARGV

ARGV — special variable

Array of command-line arguments.

# ENVIRON

ENVIRON — special variable

Array of the process environment variables.

# CONVFMT

CONVFMT — special variable

Conversion format for numbers used as strings (default "%.6g").

# OFMT

OFMT — special variable

Output format for numbers in print (default "%.6g").

# IGNORECASE

IGNORECASE — special variable

When non-zero, regex and string comparisons ignore case (gawk).

# FIELDWIDTHS

FIELDWIDTHS — special variable

Space-separated fixed field widths for parsing (gawk).

# FPAT

FPAT — special variable

Regexp describing field contents, as an alternative to FS (gawk).

# PROCINFO

PROCINFO — special variable

Array of process/runtime information (gawk).

# RT

RT — special variable

Text matched by RS for the current record (gawk).

# ERRNO

ERRNO — special variable

Description of the last getline/close/system error (gawk).

# TEXTDOMAIN

TEXTDOMAIN — special variable

Text domain for string translation (gawk).

# BINMODE

BINMODE — special variable

Binary I/O mode control (gawk).

# LINT

LINT — special variable

Dynamic control of lint warnings (gawk).

# BEGIN

BEGIN — keyword

Special pattern whose action runs once before any input is read.

# END

END — keyword

Special pattern whose action runs once after all input is consumed.

# BEGINFILE

BEGINFILE — keyword

Pattern whose action runs before each input file is read (gawk).

# ENDFILE

ENDFILE — keyword

Pattern whose action runs after each input file is processed (gawk).

# function

function — keyword

Define a user function: function name(params) { body }.

# if

if — keyword

Conditional statement: if (cond) stmt with an optional else branch.

# else

else — keyword

The alternative branch taken when an if condition is false.

# while

while — keyword

Loop that repeats stmt while cond is true: while (cond) stmt.

# for

for — keyword

Loop: for (init; cond; incr) stmt, or for (key in array) stmt.

# do

do — keyword

Do-while loop: do stmt while (cond); the body runs at least once.

# break

break — keyword

Exit the innermost for, while, or do loop immediately.

# continue

continue — keyword

Skip to the next iteration of the innermost loop.

# next

next — keyword

Stop processing the current record and read the next one.

# nextfile

nextfile — keyword

Stop processing the current input file and advance to the next.

# exit

exit — keyword

Stop reading input and run END; exit [expr] sets the exit status.

# return

return — keyword

Return from a user function, optionally with a value: return [expr].

# delete

delete — keyword

Remove an array element (delete arr[k]) or clear it (delete arr).

# switch

switch — keyword

Multi-way branch on a value: switch (expr) { case ...: ... } (gawk).

# case

case — keyword

A labeled branch inside a switch statement (gawk).

# default

default — keyword

The fallback branch taken when no case matches in a switch (gawk).

# in

in — keyword

Array membership test (key in arr) or iteration (for (key in arr)).