As mawk executes the program, it maintains a reference to the command to execute in cdp. After that there may be data and/or references in cdp[0], cdp[1], etc.

When an operation requires operands, mawk pushes the values (or array/string references) onto the stack, which updates the stack pointer sp. When the operation completes, mawk consumes those entries on the stack, pushing the result (if any) onto the stack.

While executing user-defined functions, mawk maintains a frame pointer fp to address the function's local variables.

a_cat

Concatenate array-indices.

Usage:

Forms a multiple array index by concatenating the elements of sp[1-cnt..0], with each element separated by SUBSEP.

Parameters:

cdp[0]

cnt, the number of elements to concatenate follows the command.

sp[0]..sp[1-cnt]

hold reference to the elements to concatenate.

Returns the index in sp[0].

a_del

Delete an array item.

Usage:

delete array[expr]

Parameters:

sp[0]

points to array

sp[-1]

is an expr

a_length

Find the length of an array.

Usage:

length(array)

Parameters:

sp[0]

points to array.

Returns the length of the array in sp[0].

a_pusha

Push array address onto stack.

Usage:

This is used to set up a calling argument for a function.

Parameters:

cdp[0]

array reference follows the command.

Returns the array in sp[0].

a_test

Test if an expression is present in an array.

Usage:

(expression in array)

Parameters:

sp[0]

points to an array.

sp[-1]

is an expression.

Returns 1 in sp[0] if the expression is found, 0 otherwise.

add

Add two numbers.

Usage:

first + second

Parameters:

sp[0]

holds the second value.

sp[-1]

holds the first value.

Returns the sum in sp[0].

add_asg

Combined addition/assignment.

Usage:

target += source

Parameters:

sp[0]

is the source expression

sp[-1]

points to the target

Stores the sum in the target, leaving sp[0] pointing to the target.

ae_pusha

Push reference to array cell, given expression for its index.

Usage:

arrayname[expression]

Parameters:

cdp[0]

an array reference follows the command.

sp[0]

has an expression, used for the index of a cell in the array.

Returns a reference to the addressed cell in sp[0].

ae_pushi

Push contents of array cell, given expression for its index.

Usage:

arrayname[expression]

Parameters:

sp[0]

has an expression, used for the index of a cell in the array.

Returns contents of the addressed cell in sp[0].

aloop

Update reference to next cell for array loop.

Usage:

for ( i in arrayname ) statement

Parameters:

none

Mawk maintains a stack of array-loop state. It updates the array/cell references in the current loop's state.

assign

Assigns a value.

Usage:

target = source

Parameters:

sp[0]

is the source expression

sp[-1]

points to the target

Stores the sum in the target, leaving sp[0] pointing to the target.

atan2

Compute arc-tangent of two values.

Usage:

atan2( first, second )

Parameters:

sp[0]

holds the second value

sp[-1]

holds the first value

Returns the result in sp[0].

call

Call a function.

Usage:

function()

Parameters:

cdp[0]

is a reference to the function block

cdp[1]

holds number of input arguments

Returns function value in sp[0].

cat

Concatenate two strings.

Usage:

first second

Parameters:

sp[0]

is the second string.

sp[-1]

is the first string.

Returns the result in sp[0].

close

Close the file or pipe associated with an expression.

Usage:

close( expression )

Parameters:

sp[0]

holds the expression identifying the file to close

Returns the status from closing the file, 0 on success or -1 on failure.

cos

Compute the cosine of a value in radians.

Usage:

cos( value )

Parameters:

sp[0]

is the value.

Returns the result in sp[0].

del_a

Delete an array.

Usage:

delete(array)

Parameters:

sp[0]

is the array to delete.

div

Divide one number by another.

Usage:

first / second

Parameters:

sp[0]

is the second value.

sp[-1]

is the first value.

Returns the quotient in sp[0].

div_asg

Combined division/assignment.

Usage:

target /= source

Parameters:

sp[0]

is the source

sp[-1]

points to the target

Stores the quotient in the target, leaving sp[0] pointing to the target.

eq

Compare two values.

Usage:

first == second

Parameters:

sp[0]

is the second value

sp[-1]

is the first value

Returns 1 in sp[0] if the values are equal, otherwise 0.

exit

Exits mawk with a specific exit-code.

Usage:

exit(exit_code)

Parameters:

sp[0]

is the exit_code

exit0

Exits mawk with success

Usage:

exit

Parameters:

none

exp

Compute base-e exponential function of a value.

Usage:

exp( value )

Parameters:

sp[0]

is the value

Returns the result in sp[0].

f_add_asg

Combination addition/assignment to NF.

Usage:

NF += expression

Parameters:

sp[0]

is the expression to add

f_assign

Assign an expression to NF.

Usage:

NF = expression

Parameters:

sp[0]

is the expression

f_div_asg

Combination division/assignment to NF.

Usage:

NF /= expression

Parameters:

sp[0]

is the expression

f_mod_asg

Combination modulus/assignment to NF.

Usage:

NF %= expression

Parameters:

sp[0]

is the expression

f_mul_asg

Combination multiplication/assignment to NF.

Usage:

NF *= expression

Parameters:

sp[0]

is the expression

f_post_dec

Post-decrement using NF.

Usage:

NF--

Parameters:

holds a reference to the field to use

f_post_inc

Post-increment using NF.

Usage:

NF++

Parameters:

holds a reference to the field to use

f_pow_asg

Exponentiation using NF.

Usage:

NF ^= expression

Parameters:

sp[0]

is the expression to use

f_pre_dec

Predecrement using NF.

Usage:

--NF

Parameters:

sp[0]

holds a reference to the field to use

f_pre_inc

Preincrement using NF.

Usage:

++NF

Parameters:

sp[0]

holds a reference to the field to use

f_pusha

Push array reference to data split-up as fields..

Usage:

$0 = expression
getline

Parameters:

cdp[0]

is a reference to the data to be split/assigned.

Returns the resulting array reference in sp[0].

f_pushi

Push contents of numbered field.

Usage:

$expression

Parameters:

cdp[0]

holds a reference to $expression

cdp[1]

holds expression

Returns the field's value in sp[0].

f_sub_asg

Combination subtraction/assignment to NF.

Usage:

NF -= expression

Parameters:

sp[0]

holds a reference to the field to use

fe_pusha

Push reference to numbered field.

Usage:

$number

Parameters:

sp[0]

holds the field number

Returns a reference to the field in sp[0].

fe_pushi

Push content of numbered field.

Usage:

$number

Parameters:

sp[0]

holds the field number

Returns the field's content in sp[0].

fflush

Flush the output file or pipe associated with an expression.

Usage:

fflush( expression )

Parameters:

sp[0]

is the expression value

Returns the result in sp[0].

gt

Test if first value is greater than the second.

Usage:

first > second

Parameters:

sp[0]

holds the second value.

sp[-1]

holds the first value.

Returns 1 in sp[0] if the first value is greater than, otherwise 0.

gte

Test if first value is greater than or equal to the second.

Usage:

first >= second

Parameters:

sp[0]

holds the second value.

sp[-1]

holds the first value.

Returns 1 in sp[0] if the first value is greater than or equal, otherwise 0.

index

Find the position of the second string in the first.

Usage:

index( first, second )

Parameters:

sp[0]

is the second string

sp[0]

is the first string

Returns the position in sp[0] starting at 1 if found, 0 if not found.

int

Returns a value truncated towards zero..

Usage:

int( value )

Parameters:

sp[0]

is the value

Returns the result in sp[0].

jmain

Go from BEGIN code to MAIN code.

Usage:

(internal state)

Parameters:

none

jmp

Jump to a new byte-code position, by a given number of bytes.

Usage:

(internal state)

Parameters:

cdp[0]

holds the (signed) number of bytes by which to jump.

jnz

Jump to a new byte-code position if sp[0] is nonzero, by a given number of bytes.

Usage:

(internal state)

Parameters:

cdp[0]

holds the (signed) number of bytes by which to jump.

sp[0]

holds a value to compare against 0.

jz

Jump to a new byte-code position if sp[0] is zero, by a given number of bytes.

Usage:

(internal state)

Parameters:

cdp[0]

holds the (signed) number of bytes by which to jump.

sp[0]

holds a value to compare against 0.

l_pusha

Push a local address onto the evaluation stack.

Usage:

(internal state)

Parameters:

cdp[0]

holds the offset from the frame pointer fp.

Returns the address in sp[0].

l_pushi

Push contents of a local variable onto the evaluation stack.

Usage:

(internal state)

Parameters:

cdp[0]

holds the offset from the frame pointer fp.

Returns the contents of the local variable in sp[0].

la_pusha

Pushes a reference to an array onto the evaluation stack.

Usage:

arrayname

Parameters:

cdp[0]

holds the offset from the frame pointer fp of a reference to an array.

Returns a reference to the array in sp[0].

lae_pusha

Pushes a reference to a given array cell onto the evaluation stack.

Usage:

arrayname[expression]

Parameters:

cdp[0]

holds the offset from the frame pointer fp of a reference to an array.

sp[0]

holds an expression

Returns a reference to the specified array cell in sp[0].

lae_pushi

Pushes the contents of a given array cell onto the evaluation stack.

Usage:

arrayname[expression]

Parameters:

cdp[0]

holds the offset from the frame pointer fp of a reference to an array.

sp[0]

holds an expression

Returns the contents of the specified array cell in sp[0].

length

Returns the length of a string or array value.

Usage:

length( value )

Parameters:

sp[0]

is the string or array reference

Returns the length in sp[0].

ljnz

Special jump for logical-OR, always preceded by test.

Usage:

(internal state)

Parameters:

cdp[0]

holds the (signed) number of bytes by which to jump if the value is nonzero.

sp[0]

holds a value to compare against 0.

ljz

Special jump for logical-OR, always preceded by test.

Usage:

(internal state)

Parameters:

cdp[0]

holds the (signed) number of bytes by which to jump if the value is zero.

sp[0]

holds a value to compare against 0.

log

Compute the natural logarithm of a value.

Usage:

log( value )

Parameters:

sp[0]

is the value

Returns the result in sp[0].

lt

Test if first value is less than the second.

Usage:

first < second

Parameters:

sp[0]

holds the second value.

sp[-1]

holds the first value.

Returns 1 in sp[0] if the first value is less than, otherwise 0.

lte

Test if first value is less than or equal to the second.

Usage:

first <= second

Parameters:

sp[0]

holds the second value.

sp[-1]

holds the first value.

Returns 1 in sp[0] if the first value is less than or equal, otherwise 0.

match0

Test if $0 matches a given regular expression.

Usage:

$0 ~ regex

Parameters:

cdp[0]

holds a reference to a regular expression.

Returns 1 in sp[0] if $0 matches the regular expression, 0 otherwise.

match1

Test if a given expression matches a given regular expression.

Usage:

expression ~ regex

Parameters:

cdp[0]

holds a reference to a regular expression.

sp[0]

holds an expression to test.

Returns 1 in sp[0] if the expression matches the regular expression, 0 otherwise.

match2

Test if an expression in sp[-1] matches the regular expression in sp[0].

Usage:

expression ~ regex

Parameters:

sp[0]

holds a reference to a regular expression.

sp[-1]

holds an expression to test.

Returns 1 in sp[0] if the expression matches the regular expression, 0 otherwise.

mktime

Converts a date specification in systime format to a timestamp.

Usage:

mktime( string )

Parameters:

sp[0]

holds the date-specification string

Returns the result in sp[0].

mod

Compute modulus/remainder with two operands.

Usage:

first % second

Parameters:

sp[0]

holds the second operand

sp[-1]

holds the first operand

Returns the remainder in sp[0].

mod_asg

Assign modulus/remainder with two operands.

Usage:

first %= second

Parameters:

sp[0]

holds the second operand

cdp[0]

holds the first operand

Returns the remainder in sp[0] as well as replacing the first value.

mul

Compute product with two operands.

Usage:

first * second

Parameters:

sp[0]

holds the second value

sp[-1]

holds the first value

Returns the product in sp[0].

mul_asg

Assign product with two operands.

Usage:

first *= second

Parameters:

sp[0]

holds the second value

sp[-1]

holds the first value

Returns the product in sp[0] as well as replacing the first value.

neq

Compare two values.

Usage:

first != second

Parameters:

sp[0]

is the second value

sp[-1]

is the first value

Returns 1 in sp[0] if the values are not equal, otherwise 0.

next

Read the next record, restart pattern testing.

Usage:

next

Parameters:

none

nextfile

Begin processing the next file listed on the command line.

Usage:

nextfile

Parameters:

none

nf_pushi

Push the number of fields (NF) onto the evaluation stack.

Usage:

(internal state)

Parameters:

none

not

Compute a logical negation.

Usage:

! value

Parameters:

sp[0]

holds a value to negate.

Returns the result on the evaluation stack, i.e., 0 if the value is nonzero and 1 otherwise.

ol_gl

Read into $0 using getline.

Usage:

getline

Parameters:

none

ol_gl_nr

Read into $0 using getline, updating NR and FNR.

Usage:

getline < file

Parameters:

none

omain

Start executing the main section of the script (between BEGIN and END).

Usage:

(internal state)

Parameters:

none

pop

Pop the evaluation stack, discarding the value.

Usage:

(internal state)

Parameters:

none

pop_al

Finish an array in loop, deallocating the state information.

Usage:

(internal state)

Parameters:

none

post_dec

Post-decrement a value.

Usage:

value --

Parameters:

sp[0]

holds the value to decrement

Returns the updated value in sp[0].

post_inc

Post-increment a value.

Usage:

value ++

Parameters:

sp[0]

holds the value to increment

Returns the updated value in sp[0].

pow

Compute the first value raised to the power of the second value.

Usage:

first ^ second

Parameters:

sp[0]

holds the second value

sp[-1]

holds the first value

Returns the result in sp[0].

pow_asg

Assign the first value raised to the power of the second value.

Usage:

variable = first ^ second

Parameters:

cdp[0]

is a reference to the variable which will be assigned the result

sp[0]

holds the second value

sp[-1]

holds the first value

pre_dec

Pre-decrement a value.

Usage:

-- value

Parameters:

sp[0]

holds the value to decrement.

Returns the updated value in sp[0];.

pre_inc

Pre-increment a value.

Usage:

++ value

Parameters:

sp[0]

holds the value to decrement.

Returns the updated value in sp[0];.

pusha

Push array address onto stack.

Usage:

(internal state)

Parameters:

cdp[0]

array reference follows the command.

Returns the array in sp[0].

pushc

Push a data cell onto the evaluation stack.

Usage:

(internal state)

Parameters:

cdp[0]

is a reference to the data to push

Returns a reference to the result in sp[0].

pushd

Push a double floating value onto the evaluation stack.

Usage:

(internal state)

Parameters:

cdp[0]

is a reference to the data to push

Returns a reference to the result in sp[0].

pushi

Push contents of next referenced variable onto the evaluation stack.

Usage:

(internal state)

Parameters:

cdp[0]

is a reference to the data cell to copy.

Returns a reference to the result in sp[0].

pushint

Reserve the next slot on the evaluation stack, setting its type.

Usage:

(internal state)

Parameters:

cdp[0]

holds the type to set in the new slot, e.g., for data via I/O redirection

Returns a reference to the result in sp[0].

pushs

Push a reference to a string value onto the evaluation stack.

Usage:

(internal state)

Parameters:

cdp[0]

holds a reference to the string value

Returns a reference to the result in sp[0].

rand

Returns a random number between zero and one..

Usage:

rand()

Parameters:

none

Returns the result in sp[0].

range

Test a range pattern: pat1, pat2 { action }.

Usage:

(internal state)

Parameters:

cdp[0].op

a flag, test pat1 if on else pat2

cdp[1].op

offset of pat2 code from cdp

cdp[2].op

offset of action code from cdp

cdp[3].op

offset of code after the action from cdp

cdp[4]

start of pat1 code

sp[0]

holds arguments for the action.

ret

Return a function value.

Usage:

return value

Parameters:

sp[0]

holds the return value

When calling a function, mawk saves the current stack, creating a new one. On return, mawk restores the previous stack and returns the function value in sp[0].

ret0

Return from a function without providing a return-value.

Usage:

return

Parameters:

sp[0]

is modified to make the value uninitialized.

As in the ret operation, mawk restores the previous stack. After the return, sp[0] is an uninitialized value.

set_al

Begin an array in loop.

Usage:

for ( iterator in arrayname ) statement

Parameters:

sp[0]

holds a reference to the array

sp[-1]

holds a reference to the iteration variable

Mawk pushes a new entry onto the array loop stack, and updates cdp to point to the statement to execute.

sin

Compute the sine of a value in radians.

Usage:

sin( value )

Parameters:

sp[0]

holds the value

Returns the result in sp[0].

sprintf

Returns a string constructed from expression-list according to format.

Usage:

sprintf( format [, value1 [,... ] ] )

Parameters:

sp[0]

is the last parameter value; there can be up to 255.

Returns the resulting string in sp[0].

sqrt

Returns the square root of a value.

Usage:

sqrt( value 0

Parameters:

sp[0]

is the value

Returns the result in sp[0].

srand

Seeds the random number generator.

Usage:

srand( value )
srand( )

Parameters:

sp[0]

is the seed value, which may be uninitialized

Returns the previous seed value in sp[0].

stop

Finish a range pattern.

Usage:

(internal state)

Parameters:

none

strftime

Formats the given timestamp using the given format.

Usage:

strftime( format , timestamp , utc )
strftime( format , timestamp )
strftime( format )
strftime( )

Parameters:

Zero to three parameters may be on the stack. If all three are used, they are as follows:

sp[0]

is the utc flag

sp[-1]

is the timestamp value

sp[-2]

is the format

Returns the result in sp[0].

sub

Subtract the second value from the first.

Usage:

first - second

Parameters:

sp[0]

holds the second value

sp[-1]

holds the first value

Returns the result in sp[0].

sub_asg

Assign the difference of two values to a variable.

Usage:

target = first - second

Parameters:

cdp[0]

holds a reference to the variable to which to assign the result

sp[0]

holds the second value

sp[-1]

holds the first value

Stores the difference in the target, leaving sp[0] pointing to the target.

substr

eturns the substring of string s, starting at index i, of length n.

Usage:

substr(s,i,n)
substr(s,i)

Parameters:

Two or three parameters may be on the stack. If all three are used, they are as follows:

sp[0]

holds the length n.

sp[0]

holds the index i.

sp[0]

holds the string s.

system

Executes a command, returning the wait-status.

Usage:

status = system( command )

Parameters:

sp[0]

is the command to execute

Returns the wait-status in sp[0].

systime

Returns the current time of day as the number of seconds since the Epoch.

Usage:

systime( )

Parameters:

none

Returns the result in sp[0].

test

Test a logical expression.

Usage:

value

Parameters:

sp[0]

holds a value to test.

Returns the result on the evaluation stack, i.e., 1 if the value is nonzero and 0 otherwise.

tolower

Copy a string, converting to lowercase.

Usage:

tolower( value )

Parameters:

sp[0]

is the value to convert

Returns the result in sp[0].

toupper

Copy a string, converting to uppercase.

Usage:

toupper( value )

Parameters:

sp[0]

is the value to convert

Returns the result in sp[0].

uminus

Unitary minus.

Usage:

- value

Parameters:

sp[0]

contains a value to negate. As a side-effect, if the value is a string, it is cast to double floating point.

Returns the result in sp[0].

uplus

Unitary plus.

Usage:

+ value

Parameters:

sp[0]

contains a value to use. As a side-effect, if the value is a string, it is cast to double floating point.

Returns the result in sp[0].

M_1J

mandatory jump

M_2JA

optional (undesirable) jump

M_2JB

optional (desirable) jump

M_2JC

pop pos'n, optional jump if advanced

M_ACCEPT

end of match

M_ANY

arbitrary character (.)

M_CLASS

character class

M_END

end of string ($)

M_SAVE_POS

push position onto stack

M_START

start of string (^)

M_STR

matching a literal string

M_U

arbitrary string (.*)