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AWK syntax:awk [-Fs] "program" [file1 file2...] # commands come
from DOS cmdlineawk 'program{print "foo"}' file1 # single quotes
around double quotes# NB: Don't use single quotes alone if the
embedded info will contain the# vertical bar or redirection arrows!
Either use double quotes, or (if# using 4DOS) use backticks around
the single quotes: `'NF>1'`
# NB: since awk will accept single quotes around arguments from
the# DOS command line, this means that DOS filenames which contain
a# single quote cannot be found by awk, even though they are legal
names# under MS-DOS. To get awk to find a file named foo'bar, the
name must# be entered as foo"'"bar.
awk [-Fs] -f pgmfile [file1 file2...] # commands come from DOS
file
If file1 is omitted, input comes from stdin (console).Option -Fz
sets the field separator FS to letter "z".
AWK notes:
"pattern {action}"if {action} is omitted, {print $0} is
assumedif "pattern" is omitted, each line is selected for
{action}.
Fields are separated by 1 or more spaces or tabs: "field1
field2"If the commands come from a file, the quotes below can be
omitted.
Basic AWK commands:-------------------"NR == 5" file show rec.
no. (line) 5. NB: "==" is equals.{FOO = 5} single = assigns "5" to
the variable FOO"$2 == 0 {print $1}" if 2d field is 0, print 1st
field"$3 < 10" if 3d field < 10, numeric comparison; print
line
'$3 < "10" ' use single quotes for string comparison!, or-f
pgmfile [$3 < "10"] use "-f pgmfile" for string comparison"$3 ~
/regexp/" if /regexp/ matches 3d field, print the line'$3 ~
"regexp" ' regexp can appear in double-quoted string*
# * If double-quoted, 2 backslashes for every 1 in regexps# *
Double-quoted strings require the match (~) character.
"NF > 4" print all lines with 5 or more fields"$NF > 4"
print lines where the last field is 5 or more"{print NF}" tell us
how many fields (words) are on each line"{print $NF}" print last
field of each line
"/regexp/" Only print lines containing "regexp"
"/textfile/" Lines containing "text" or "file" (CASE
SENSITIVE!)
"/foo/{print "za", NR}" FAILS on DOS/4DOS command
line!!'/foo/{print "za", NR}' WORKS on DOS/4DOS command line!!
If lines matches "foo", print word and line no.`"/foo/{print
\"za\",NR}"` WORKS on 4DOS cmd line: escape internal quotes
with
slash and backticks; for historical interest only.
"$3 ~ /B/ {print $2,$3}" If 3d field contains "B", print 2d + 3d
fields"$4 !~ /R/" Print lines where 4th field does NOT contain
"R"
'$1=$1' Del extra white space between fields & blank
lines'{$1=$1;print}' Del extra white space between fields, keep
blanks
'NF' Del all blank lines
AND(&&), OR(), NOT(!)
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-----------------------"$2 >= 4 $3 5 && /with/" lines
containing "with" for lines 6 or beyond"/x/ && NF > 2"
lines containing "x" with more than 2 fields
"$3/$2 != 5" not equal to "value" or "string""$3 !~ /regexp/"
regexp does not match in 3d field
"!($3 == 2 && $1 ~ /foo/)" print lines that do NOT match
condition
"{print NF, $1, $NF}" print no. of fields, 1st field, last
field"{print NR, $0}" prefix a line number to each line'{print NR
": " $0}' prefix a line number, colon, space to each line
"NR == 10, NR == 20" print records (lines) 10 - 20,
inclusive"/start/, /stop/" print lines between "start" and
"stop"
"length($0) > 72" print all lines longer than 72 chars"{print
$2, $1}" invert first 2 fields, delete all others"{print
substr($0,index($0,$3))}" print field #3 to end of the line
END{...} usage--------------- END reads all input first.
1) END { print NR } # same output as "wc -l"
2) {s = s + $1 } # print sum, ave. of all figures in col. 1END
{print "sum is", s, "average is", s/NR}
3) {names=names $1 " " } # converts all fields in col 1 toEND {
print names } # concatenated fields in 1 line, e.g.
+---Beth 4.00 0 #
input Mary 3.75 0 # infile is converted to:file Kathy 4.00 10 #
"Beth Mary Kathy Mark" on output
+---Mark 5.00 30 #
4) { field = $NF } # print the last field of the last lineEND {
print field }
PRINT, PRINTF: print expressions, print formattedprint expr1,
expr2, ..., exprn # parens() needed if the expression
containsprint(expr1, expr2, ..., exprn) # any relational operator:
=
print # an abbreviation for {print $0}print "" # print only a
blank lineprintf(expr1,expr2,expr3,\n} # add newline to printf
statements
FORMAT CONVERSION:------------------BEGIN{ RS=""; FS="\n"; #
takes records sep. by blank lines, fields
ORS="\n"; OFS="," } # sep. by newlines, and converts to
records{$1=$1; print } # sep. by newlines, fields sep. by
commas.
PARAGRAPHS:-----------'BEGIN{RS="";ORS="\n\n"};/foo/' # print
paragraph if 'foo' is there.
'BEGIN{RS="";ORS="\n\n"};/foo/&&/bar/' # need
both;/foobar/' # need either
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PASSING VARIABLES:------------------gawk -v var="/regexp/"
'var{print "Here it is"}' # var is a regexpgawk -v var="regexp"
'$0~var{print "Here it is"}' # var is a quoted stringgawk -v num=50
'$5 == num' # var is a numeric value
Built-in variables:
ARGC number of command-line argumentsARGV array of command-line
arguments (ARGV[0...ARVC-1])FILENAME name of current input fileFNR
input record number in current fileFS input field separator
(default blank)NF number of fields in current input recordNR input
record number since beginningOFMT output format for numbers
(default "%.6g")OFS output field separator (default blank)ORS
output record separator (default newline)RLENGTH length of string
matched by regular expression in matchRS input record separator
(default newline)
RSTART beginning position of string matched by matchSUBSEP
separator for array subscripts of form [i,j,...] (default ^\)
Escape sequences:\b backspace (^H)\f formfeed (^L)\n newline
(DOS, CR/LF; Unix, LF)\r carriage return\t tab (^I)\ddd octal value
`ddd', where `ddd' is 1-3 digits, from 0 to 7\c any other character
is a literal, eg, \" for " and \\ for \
Awk string functions:
`r' is a regexp, `s' and `t' are strings, `i' and `n' are
integers`&' in replacement string in SUB or GSUB is replaced by
the matched string
gsub(r,s,t) globally replace regex r with string s, applied to
data t;return no. of substitutions; if t is omitted, $0 is
used.
gensub(r,s,h,t) replace regex r with string s, on match number
h, appliedto data t; if h is 'g', do globally; if t is omitted, $0
isused. Return the converted pattern, not the no. of changes.
index(s,t) return the index of t in s, or 0 if s does not
contain tlength(s) return the length of smatch(s,r) return index of
where s matches r, or 0 if there is no
match; set RSTART and RLENGTHsplit(s,a,fs) split s into array a
on fs, return no. of fields; if fs is
omitted, FS is used in its placesprintf(fmt,expr-list) return
expr-list formatted according to fmtsub(r,s,t) like gsub but only
the first matched substring is replacedsubstr(s,i,n) return the
n-character substring of s starting at i; if n
is omitted, return the suffix of s starting at i
Arithmetic functions:atan2(y,x) arctangent of y/x in radians in
the range of - to cos(x) cosine (angle in radians)exp(n)
exponential e (n need not be an integer)int(x) truncate to
integerlog(x) natural logarithm
rand() pseudo-random number r, 0 r 1sin(x) sine (angle in
radians)sqrt(x) square root
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srand(x) set new seed for random number generator; uses time of
dayif no x given
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