AwkChannelWiki: Search for: "variable"

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AA-awk-history
http://awk.freeshell.org/AA-awk-history\\ a concise history of awk and some of its forks\\ {{{ common . . . sub gsub\\       variables: ARGC ARGV FNR RSTART RLENGTH SUBSEP\\   . . .
2K - last updated 2013-10-26 02:28 UTC by g0ph3r

Adler32Checksum
As documented in the [[http://en.wikipedia.org/wiki/Adler-32 | Adler-32 Wikipedia article]]. {{{ awk . . . scoping and no ability to # query whether a variable has been defined, so we can't check for # . . .
4K - last updated 2008-12-31 12:05 UTC by pgas

AllAboutGetline
//Editor's notes: The article was originally posted on the comp.lang.awk newsgroup, and can still be . . . variants of getline applications, listing which variables are set by each one: |=Variant|=Variables . . . gawk also populates the ERRNO builtin variable if getline fails. Although calling getline . . . }}} since those do not affect any of the builtin variables and they allow you to correctly test for . . . above set some but not all of the builtin variables, so you need to be very careful that it's . . .
16K - last updated 2009-02-15 22:14 UTC by waldner

assign
== The assignment operator == In [[awk]], as with most other programming languages, the *equals sign* . . . of the right hand [[operand]] to the [[variable]] named by the left [[operand]]: == Assignment . . . of variables == The following examples show the use of . . . the equals sign for the assignment of [[variable]]s: {{{ fruit = "apple" # assign a string . . . to a variable count = 5 # assign a numeric value to a variable . . .
1K - last updated 2010-11-28 18:17 UTC by markhobley

AwkDc
This is an awk implementation of the [http://www.gnu.org/software/bc/manual/dc-1.05/html_mono/dc.html|dc] . . . error message here # FIXME: take into account variable overflow } } function _dc_div(stk, tos1, tos2) . . . error message here # FIXME: take into account variable precision } } function _dc_mod(stk, tos1, . . .
12K - last updated 2008-07-17 14:47 UTC by gnomon

AwkGuide
** Work in Progress ** {{{ import from Mark Hobley's wiki }}} <toc> ---- == Overview * [[Overview]] . . . * [[conditional loop]]s * [[read only variable|constant]]s * [[constructor]]s * [[context]] . . . * [[datatype]]s * [[declaration]] * [[default variable]] * [[define functions]] * [[delimiter]]s . . . * quotient [[division]] * [[read only variable]]s * [[record]]s * [[redirection]] * [[RS|record . . . * [[rule]]s * [[search pattern]]s * [[special variable]]s * [[statement]]s * [[string]]s * [[string . . .
4K - last updated 2011-08-14 15:57 UTC by markhobley

AwkOnWindowsHowto
AwkOnWindowsHowto\\ rough cut - needs edit {{{ 3) awk command line switches/usage from a win32 cmd.exe . . . var=value -v a=1 to be done NOW. one -v for each variable (\a \v \xhh Not interpreted in value; use . . . /dev/stderr array SYMTAB holds values of variables for(varname in SYMTAB) \ if ((varname != . . .
3K - last updated 2010-10-24 07:44 UTC by g0pher

AwkTips
<toc> ---- == Be idiomatic! In this paragraph, we give some hints on how to write more idiomatic . . . are specified on the command line. The special variable NR stores the total number of input records . . . increases until the program terminates. Another variable, FNR, stores the number of records read //from . . . The "-v n=1" is used to tell awk that the variable "n" should be initialized with a value of . . . }}} Yet another way is to exploit awk's internal variable typing to check that n is indeed a number . . .
31K - last updated 2009-03-24 16:54 UTC by waldner

AwkVsPerl
A valid question, since awk is a subset of perl (functionally, not necessarily syntactically); also, . . . much quicker to execute for small programs * awk variables don't have `$' in front of them :-) * clear . . .
2K - last updated 2011-01-22 05:33 UTC by steve

AwkVsPerlJapanese
A valid question, since awk is a subset of perl (functionally, not necessarily syntactically); also, . . . much quicker to execute for small programs * awk variables don't have `$' in front of them :-) * clear . . .
2K - last updated 2008-11-24 08:05 UTC by pgas

BeforeAfterMatch
Problem: print the Nth record before or after a certain regular expression matches or, alternativley, . . . make the solutions generic, you can pass N as a variable, eg {{{ sh awk -v N=3 '/pattern/{a[NR+N]}; . . .
3K - last updated 2009-02-28 20:38 UTC by waldner

BEGIN
== Begin Blocks The [[awk]] programming language allows us to use **begin blocks** and **end blocks** . . . blocks** are typically used to initialize [[variable]]s, such as the [[RS|record separator]] and . . . the END rule may need to check the FNR and NR variables. Older versions of awk may read the input . . . in order that they are defined. == Special Variables === FILENAME Normally the FILENAME variable . . .
3K - last updated 2013-04-11 14:25 UTC by 92.40.253.171.threembb.co.uk

case conversion
The [[awk]] extraction and reporting language provides the toupper and tolower functions for converting . . . are affected by the following locale environment variable settings. * LC_ALL * LC_CTYPE . . .
2K - last updated 2011-06-25 05:10 UTC by pgas

case sensitivity
== Indentifier names == The [[awk]] interpreter is lettercase sensitive. This means that [[variable name]]s . . . identifiers dog,Dog and DOG represent separate variables BEGIN { dog = "Benjamin" Dog = "Samba" DOG . . .
1K - last updated 2011-06-25 05:14 UTC by pgas

command line parameter
The [[awk]] extraction and reporting language uses traditional conventions for accessing command line . . . of parameters are stored in the [[scalar]] variable ARGC. {{{ awk #!/usr/bin/awk -f BEGIN { print . . .
1K - last updated 2011-06-25 05:49 UTC by pgas

comp.lang.awk FAQ
This material of this faq originates from the comp.lang.awk FAQ that you can find there: * http://www.faqs.org/faqs/computer-lang/awk/faq/ . . . ---- == How can I access shell or environment variables in an awk script? === Shells <include . . . Edit this answer]] === Environment variables in general <include "EnvVarGeneral"> . . . Edit this answer]] === exporting environment variables back to the parent process <include "PassingVariablesToTheParentProcess"> . . . Edit this answer]] ---- . . .
8K - last updated 2009-03-04 12:42 UTC by pgas

comp.lang.awk FAQJapanese
This material of this faq originates from the comp.lang.awk FAQ that you can find there: * http://www.faqs.org/faqs/computer-lang/awk/faq/ . . . ---- == How can I access shell or environment variables in an awk script? === Shells <include . . . Edit this answer]] === Environment variables in general <include "EnvVarGeneralJapanese"> . . . Edit this answer]] === exporting environment variables back to the parent process <include "PassingVariablesToTheParentProcessJapanese"> . . . Edit this answer]] . . .
4K - last updated 2008-11-24 09:01 UTC by pgas

compound assignment operator
The *compound assignment operators* (also called *combination assignment operators*) provide a more concise . . . by enabling calculations involving a [[variable]] to be performed without the [[variable]] . . .
2K - last updated 2011-03-27 09:46 UTC by markhobley

ContextGrep
The following snippets print matching lines with surrounding context lines, like GNU grep's **grep -A . . . to save any lines. The following expects two variables to be set: **Pattern** (a regex to match), . . . of doing it (this time, the script expects the variables **Pattern** and **Before** (number of lines . . . lines[NR] = $0 # ... or save the line } }}} The variable **last** keeps track of the last line printed, . . . two previous scripts. This script expects the variables **Pattern** and **Context** (number of lines . . .
3K - last updated 2011-07-01 08:32 UTC by pgas

dollarint
A [[dollar]] sign and followed by an [[integer]] are used to refer to [[field]]s within the current [[record]]: . . . three }}} Though you might consider $3 as a variable, it's not exactly true, in fact $ is the field . . . does not need to be a [[constant]]. === Using a variable name to specify the field number === It is . . . possible to use to use a [[variable name]] after the [[dollar]] sign to specify . . . error]] will occur. == Assignment to dollarint variables == It is possible to change the contents . . .
3K - last updated 2011-06-25 05:28 UTC by pgas

enumeration
The [[awk]] extraction and reporting language does not directly support enumeration. However, it is possible . . . to simulate enumberation by using a [[variable]] and [[nudge]] operator combination. In the . . .
1K - last updated 2011-05-27 15:28 UTC by markhobley

ENVIRON
Modern versions of new awk (gawk, mawk, Bell Labs awk, any POSIX awk) all provide an array named ENVIRON. . . . The array is indexed by environment variable name; the value is that variable's value. . . .
1K - last updated 2008-11-19 13:13 UTC by pgas

ENVIRONJapanese
Modern versions of new awk (gawk, mawk, Bell Labs awk, any POSIX awk) all provide an array named ENVIRON. . . . The array is indexed by environment variable name; the value is that variable's value. . . .
1K - last updated 2008-11-24 08:05 UTC by pgas

environment
The ENVIRON [[associative container]] contains the values of the current environment. This enables an . . . environment variable to be accessed by using the environment variable . . .
1K - last updated 2011-06-07 01:05 UTC by markhobley

EnvVarGeneral
**Answer 1:** On Unix, use "alternate quoting", e.g. {{{ awk -F: '$1 ~ /'"$USER"'/ {print $5}' /etc/passwd . . . dependent on the actual content of the shell variables you are using. Some examples follow (taken . . . 2:** RTFM to see if and how your awk supports variable definitions on the command line, e.g., {{{ . . . for a very complete discussion of passing shell variables values to awk programs. . . .
3K - last updated 2011-07-05 09:31 UTC by pgas

field
In [[awk]] all [[input]] is separated into [[record]]s and each [[record]] is further divided into fields. . . . == Fields are referenced using special variables == Within the [[awk]] script, each field . . .
1K - last updated 2011-06-25 05:31 UTC by pgas

field reference
== The field reference operator == The [[dollar]] symbol acts as a unary *field reference operator* and . . . } # output field number 123 }}} ==== Using a variable name to specify the field number ==== It is . . . possible to use to use a [[variable name]] after the dollar sign to specify the . . .
2K - last updated 2011-06-28 09:12 UTC by markhobley

FieldReference
$ is the "field reference" operator in AWK. It references the field in the current input record given . . . by the variable or constant. E.g. if you want to print the . . . and a constant. print $1; # same but with a variable instead of a constant i = 1; print $i; }}} . . .
1K - last updated 2009-01-03 01:51 UTC by fcr

FileName
the file name is stored in the built-in variable FILENAME: {{{ awk '/^#include/ {print FILENAME,$2}' . . .
1K - last updated 2008-11-18 13:31 UTC by pgas

FileNameJapanese
the file name is stored in the built-in variable FILENAME: {{{ awk '/^#include/ {print FILENAME,$2}' . . .
1K - last updated 2008-11-24 08:08 UTC by pgas

FIXES
[[FIXES]]        revised:   . . . ENVIRON array contains environment: if shell variable V=thing,\\     ENVIRON["V"] . . . added -v x=1 ... for immediate commandline variable assignment;\\     done . . . awk -f - reads the program from stdin.\\ enforce variable name syntax for commandline variables:\\     has . . .
6K - last updated 2014-01-15 23:17 UTC by g0ph3r

FNR
The *FNR* informative [[special variable]] is used to track the number of [[record]]s that have so far . . . line numbers to a file === The FNR [[special variable]] can be wielded to give a simple way of adding . . .
1K - last updated 2011-05-08 11:04 UTC by markhobley

ForceNumeric
These are the canonical, work-in-all-versions snippets. There are many others, most longer, some shorter . . . (but possibly less portable). To compare two variables as numbers ONLY, use {{{ awk if (0+var1 == . . . 0+var2) }}} To compare two variables as non-numeric strings ONLY, use {{{ awk . . .
1K - last updated 2008-11-26 12:43 UTC by pgas

Frequently Asked Questions
Some entries of this page have been copied from the [[comp.lang.awk_FAQ]]([[http://awk.freeshell.org/comp.lang.awk_FAQ#toc29|Credits]]) . . . Edit this answer]] ---- == How do I use a variable as a regular expression? <include "VariablesInRegex"> . . . [[http://awk.freeshell.org/?action=edit;id=VariablesInRegex| Edit this answer]] ---- == How do . . . I pass a shell variable to awk? <include "PassingAShellVariable"> . . . Edit this answer]] ---- == How do I pass . . .
3K - last updated 2015-09-08 08:46 UTC by pgas

FS
= Field Separator = The [[special variable]] FS is a field separator that is used to determine how [[awk]] . . . be changed by [[assign]]ment like any other [[variable]]. Note that the field separator can be a . . . the default field separator to be changed. This variable can be set on the command line. === Example . . .
5K - last updated 2013-02-19 21:45 UTC by markhobley

getline
The *getline* command can obtain input from any number of files and does not require a command line parameter . . . variants of getline applications, listing which variables are set by each one: | *Variant* | *Variables . . . during the [[getline]] operation, the special variable [[ERRNO]] should becomes set and the [[awk]] . . .
1K - last updated 2011-05-02 20:14 UTC by markhobley

input
The [[awk]] utility can take its input from [[standard input]] or from [[file]]s. If no input files are . . . filename as a command line parameter. == Special variables related to input == The following [[special . . . variable]]s are related to input: | *Variable* | *Description* . . . | [[FNR]] | An informative variable that provides the record number within the . . . current file | [[FS]] | A control variable that specifies the input field separator | . . .
2K - last updated 2011-05-19 22:40 UTC by markhobley

iterative loop
An '''iterative loop''' repeatedly executes a set of instructions as the [iterator] steps through a series . . . runs for each consecutive [loop]. The [iterator] variable l, starts at zero and [increment]s on each . . .
2K - last updated 2011-08-13 21:00 UTC by markhobley

LastField
awk performs a number of actions automatically when it parses lines: it updates the variable NF, which . . . a series of fields which are accessible via the variables $1, $2, $3 and so on. The variable $0 contains . . . entire line. Though you might consider $1 as a variable, it's not exactly true, in fact $ is the field . . . $(10-9) also refers to first field. Since the variable NF contains the number of fields on a line, . . . Variables that convey information]; * [http://www.gnu.org/software/gawk/manual/html_node/Fields.html|Examining . . .
2K - last updated 2009-02-05 22:43 UTC by firebush.stsci.edu

libmawk
libmawk is a fork of [[mawk]], designed for embedding in C programs. Compare and contrast with [[awka]]. . . . from awk scripts * resolve existing awk variables from C - read or write variables * language . . . by name using call() and acall()) ** dynamic variable value fetch (valueof() returns the value of . . . a variable by name) ** include "source.awk" allows an . . .
2K - last updated 2012-01-16 09:07 UTC by lewellyn

mistake
== _Programming mistakes in awk_ * Using a [[reserved word]] for a [[variable name]] . . .
1K - last updated 2010-10-19 22:18 UTC by markhobley

MostrarApostrofos-español
Esta pregunta es tan frecuente que merece su propia respuesta. Y aunque pareciera que esto es una limitación . . . of putting a single quote character in its own variable and then using explicit string concatenation: . . .
4K - last updated 2009-01-15 20:03 UTC by fcr

NF
= Number of Fields = The [[special variable]] NF holds the number of [[field]]s in the [[current record]]. . . .
1K - last updated 2011-05-28 15:14 UTC by markhobley

nudge operator
The *nudge operators* can be used to [[increment]] or [[decrement]] the value of their [[operand]]s, . . . [[operand]]s, so the [[operand]]s must be [[variable name]]s: {{{ number++ # increment number-- . . . behaviour If the [[operator]] is used before a [[variable]] name, the [[operator]] exhibits pre-nudge . . . behaviour and the [[variable]] is changed, before the [[expression]] is . . . If the [[operator]] is used after the [[variable]] name, the [[operator]] exhibits post-nudge . . .
3K - last updated 2011-03-20 13:18 UTC by markhobley

oawk
oawk is "old awk", it is the default /usr/bin/awk on Solaris and should not be used. You can also find . . . illegal statement near line 1 }}} ==== No FNR variable: {{{sh $ cat file1 a $ cat file2 b $ /usr/xpg4/bin/awk . . . }}} ==== Strings can unexpectedly become numeric variables: {{{sh $ /usr/xpg4/bin/awk 'BEGIN{ c=3; print . . .
5K - last updated 2012-01-24 08:29 UTC by pgas

operator
The [[awk]] programming language provides a series of *operators* that allow [[value]]s and [[variable]]s . . . can combined together with [[value]]s and [[variable]]s to make [[expression]]s. The operators . . . of the right hand [[operand]] to the [[variable]] named by the left [[operand]]. == arithmetic . . .
3K - last updated 2011-05-24 22:19 UTC by markhobley

PassingAShellVariable
The common solution is to use the -v option to define an awk variable giving it the value of the shell . . . variable: {{{ sh # correct quoting for a bourne like . . . shell: shellvariable=foo awk -v awkvar="$shellvariable" 'BEGIN{print . . . awkvar}' }}} If you want to pass a pattern as a variable take care that the pattern is a string, so . . . a constant awk '/foo\./{print}' #version with a variable pattern='foo\\.' awk -v pattern="$pattern" . . .
1K - last updated 2009-01-30 08:36 UTC by pgas

PassingVariables
<toc> === Shells <include "Shells"> [[http://awk.freeshell.org/?action=edit;id=Shells| Edit . . . this answer]] === Environment variables in general <include "EnvVarGeneral"> . . . Edit this answer]] === exporting environment variables back to the parent process <include "PassingVariablesToTheParentProcess"> . . . Edit this answer]] . . .
1K - last updated 2008-11-19 07:47 UTC by pgas

PassingVariablesToTheParentProcess
How can I put values into the environment of the program that called my awk program? Short answer, you . . .
1K - last updated 2008-11-19 07:45 UTC by pgas

PassingVariablesToTheParentProcessJapanese
How can I put values into the environment of the program that called my awk program? Short answer, you . . .
1K - last updated 2008-11-24 08:05 UTC by pgas

precedence
The [[awk]] programming language uses rules of *precedence* to determine the order in which [[operator]]s . . . value outside. {{{ BEGIN { # Changing the number variable in the middle of the expression may introduce . . .
7K - last updated 2013-04-11 06:58 UTC by markhobley

PreguntasFrecuentes
<toc> ---- == ¿Cómo muestro un rango de campos? Desde [[RangoDeCampos-español]], [[http://awk.freeshell.org/es?action=edit;id=RangoDeCampos-espa%C3%B1ol| . . . ---- == ¿Por qué «print $variable» no muestra nada? ¿por qué «print "hola $nombre"» . . . no funciona? Desde [[variable-español]], [[http://awk.freeshell.org/es?action=edit;id=variable-espa%C3%B1ol|editar]]: . . . <include "variable-español"> ---- == Bien, ¿entonces, para . . .
2K - last updated 2009-01-03 03:01 UTC by fcr

PrintASingleQuote
This question gets asked often enough that it deserves its own answer. This common question doesn't actually . . . of putting a single quote character in its own variable and then using explicit string concatenation: . . . page if you know any. ====Feed the quote as a variable to awk Another way is to provide the quote . . . to awk as a variable: --single quote {{{ awk -v q="'" 'BEGIN{print . . .
5K - last updated 2015-07-05 09:45 UTC by pitman

PrintingNumbers
Use printf and a format string instead of print, some examples: {{{ awk BEGIN { printf "%f", 1000001.10 . . . like printf using the format string in the variable OFMT, which contains %.6g by default, when . . .
2K - last updated 2009-03-04 12:34 UTC by pgas

qse
Not a standalone awk, but an interesting library embedding an awk interpreter, from [[https://groups.google.com/group/comp.lang.awk/browse_thread/thread/b02c0d75e49eab75/54fc2c6316d657bc?lnk=gst&q=c%2B%2B+embed#54fc2c6316d657bc| . . . application is capable of: * adding new global variables and functions. * getting and set the value . . . of a global variable. * calling a function with or without parameters . . .
4K - last updated 2011-10-27 06:25 UTC by pgas

read only variable
=== _User defined variables cannot be marked as readonly_ The [[awk]] extraction and reporting language . . . not provide facilities for defining readonly variables. === _Informative special variables_ Some . . . informative [[special variable]]s may be readonly and cannot be explicitly . . .
1K - last updated 2011-06-01 21:29 UTC by markhobley

ReferenciarCampos-español
En AWK, $ es el operador para "referenciar campos". Justamente referencia el campo del registro de entrada . . . print $(2 * 0.5); # idéntico pero con una variable en lugar de una constante: i = 1; print $i; . . .
1K - last updated 2009-01-03 03:06 UTC by fcr

RS
= Record Separator = The [[special variable]] RS is a record separator that is used to determine how . . . can be changed by assignment like any other variable. This is often done in a begin block, before . . .
3K - last updated 2013-02-19 23:11 UTC by markhobley

ShellQuoting
Quoting can be such a headache for the novice, in shell programming, and especially in awk. Art Povelones . . . will copy verbatim, not interpreting environment variable substitutions etc.) {{{ cat <<'@@' > . . .
2K - last updated 2008-11-19 07:41 UTC by pgas

special variable
Some [[variable]] names have a special meaning to the awk interpreter. == List of special variables == . . . The following are '''special variables''' within [[awk]]: | '''Variable''' | Description . . . | [[ARGC]] | An informative variable that provides command line parameter information . . . parameter information | [[CONVFMT]] | A control variable that specifies the conversion format of numerical . . . strings | [[FILENAME]] | An informative variable that provides the current input [[filename]] . . .
2K - last updated 2011-06-25 05:46 UTC by pgas

SpecialFile
You can use `-v rulesfile=filename' to process a file differently, like you would any other variable, . . .
1K - last updated 2008-11-18 13:37 UTC by pgas

SpecialFileJapanese
You can use `-v rulesfile=filename' to process a file differently, like you would any other variable, . . .
1K - last updated 2008-11-24 08:09 UTC by pgas

truth
== Boolean Truth == A **boolean [[expression]]** has only two outcomes: **true** or **false**. In [[awk]], . . . This is a [[pitfall]] because true is a valid variable name that is initialized to 0 or "" and thus . . . # $1 is the number 0 }}} ==== Taking zero from a variable If a zero value is assigned to a variable, . . . result with var = "00" True! }}} However, if the variable was assigned in numeric context (without the . . . false. This is a caveat, because true is a valid variable name that is initialized to 0 or "". . . .
3K - last updated 2013-02-20 17:34 UTC by markhobley

variable-español
AWK no es el shell, y tampoco es Perl. Antes que nada, las variables en AWK se referencian utilizando . . . a las palabras para referirse a estas como una variable - si deseas acceder a una variable llamada . . . }}} AWK es como C (no el shell), no expande las variables dentro de los strings literales. No podría . . . dado que no hay forma para distinguir entre variables y palabras en una string literal. Por tanto . . . literal, más allá de si «nombre» es o no una variable en el script de AWK. Para formar nuevos strings . . .
2K - last updated 2009-01-03 04:02 UTC by fcr

variable
A '''variable''' is a symbolic name associated with a [[value]]. A variable acts as a container and the . . . to take place from within the [[script]]. == Variables are dynamic == In [[awk]] variables are [[dynamic]] . . . either [[numeric]] or [[string]] values. === Variables do not need predefinition prior to use === . . . awk, there is no need to declare or initialize variables before they are used. By default, variables . . . is possible == It is possible to initialize variables in a BEGIN block to make them obvious and . . .
3K - last updated 2012-04-22 11:42 UTC by unregistered

VariablesInRegex
The patterns between slashes like /pattern/ are called **ERE constants**, or **regular expressions literals**. . . . constant regular expressions. If you have a variable //var// that contains "**abc(123)?r+**" and . . .
2K - last updated 2010-11-26 08:49 UTC by 195.97.26.99

WartAndWishList
Awk is a wonderful language! That said, there are a few annoying bits... == The Good * well-documented . . . portable built-in way of querying the type of a variable: strings and numbers get automatically converted . . . no way of reliably determining the type of a variable, tracking down those performance sinks requires . . . ugly real fast]. * Awk variables are either global or parameters to a user-defined . . . so there is a convention to list local variables in the parameter list: for example, the function . . .
7K - last updated 2009-04-13 18:39 UTC by goedel

67 pages found.