interpreta ogni linea di input come un record ed ogni parola della linea come un campo.

$0             # linea in input
$1, $2, ... # i singoli campi della linea in input

awk 'instructions' files
awk -f script files

# printa il primo campo di ogni record
awk '{ print $1 }' file

# printa i record che contengono "MA"
awk '/MA/' file

# printa il primo campo dei record che contengono "MA"
awk '/MA/ { print $1 }' file

# -F per cambiare il delimitatore a ","
awk -F, { print $1 }' file 

u@anjuna:~$ > risultato.txt
maniu@securebrain:~$ for i  in `cat /home/maniu/file.txt` ; do host -t SOA $i |awk -v j=$i '{print j, $4}'>> risultato.txt; done ;
maniu@securebrain:~$ cat risultato.txt |awk ' { t=$2
>sub(/\./, "@" , t)
>print $1, t }
>'
qwerty.my hostmaster@qwerty.my.
pippo.pluto.my root@pluto.my.

# awk con if
df -k /opt /tmp /var|awk '/[0-9] total allocated Kb/ { if (fsname != 0) printf "%s %i %i\n", fsname, total, used ; total = $5 ;
  fsname = $1} /[0-9] used allocated Kb/ { used=$1} END { printf "%s %i %i\n", fsname, total, used}'

echo 1dfsdf34 |awk '{ if ( $1 ~ /^[0,1,2,3,4,5,6,7,8,9]/ ) print $1 }'

# double space a file
awk ?1;{print ??}?
awk ?BEGIN{ORS=?\n\n?};1?

# double space a file which already has blank lines in it. Output file
# should contain no more than one blank line between lines of text.
# NOTE: On Unix systems, DOS lines which have only CRLF (\r\n) are
# often treated as non-blank, and thus ?NF? alone will return TRUE.
awk ?NF{print $0 ?\n?}?

# triple space a file
awk ?1;{print ?\n?}?

NUMBERING AND CALCULATIONS:

# precede each line by its line number FOR THAT FILE (left alignment).
# Using a tab (\t) instead of space will preserve margins.
awk ?{print FNR ?\t? $0}? files*

# precede each line by its line number FOR ALL FILES TOGETHER, with tab.
awk ?{print NR ?\t? $0}? files*

# number each line of a file (number on left, right-aligned)
# Double the percent signs if typing from the DOS command prompt.
awk ?{printf(?%5d : %s\n?, NR,$0)}?

# number each line of file, but only print numbers if line is not blank
# Remember caveats about Unix treatment of \r (mentioned above)
awk ?NF{$0=++a ? :? $0};{print}?
awk ?{print (NF? ++a ? :? :?") $0}?

# count lines (emulates ?wc -l?)
awk ?END{print NR}?

# print the sums of the fields of every line
awk ?{s=0; for (i=1; i max {max=$1; maxline=$0}; END{ print max, maxline}?

# print the number of fields in each line, followed by the line
awk ?{ print NF ?:? $0 } ?

# print the last field of each line
awk ?{ print $NF }?

# print the last field of the last line
awk ?{ field = $NF }; END{ print field }?

# print every line with more than 4 fields
awk ?NF > 4?

# print every line where the value of the last field is > 4
awk ?$NF > 4?

TEXT CONVERSION AND SUBSTITUTION:


# IN UNIX ENVIRONMENT: convert DOS newlines (CR/LF) to Unix format
awk ?{sub(/\r$/,?");print}? # assumes EACH line ends with Ctrl-M

# IN UNIX ENVIRONMENT: convert Unix newlines (LF) to DOS format
awk ?{sub(/$/,?\r?);print}

# IN DOS ENVIRONMENT: convert Unix newlines (LF) to DOS format
awk 1

# IN DOS ENVIRONMENT: convert DOS newlines (CR/LF) to Unix format
# Cannot be done with DOS versions of awk, other than gawk:
gawk -v BINMODE=?w? ?1? infile >outfile

# Use ?tr? instead.
tr -d \r outfile # GNU tr version 1.22 or higher

# delete leading whitespace (spaces, tabs) from front of each line
# aligns all text flush left
awk ?{sub(/^[ \t]+/, ??); print}?

# delete trailing whitespace (spaces, tabs) from end of each line
awk ?{sub(/[ \t]+$/, ??);print}?

# delete BOTH leading and trailing whitespace from each line
awk ?{gsub(/^[ \t]+|[ \t]+$/,?");print}?
awk ?{$1=$1;print}? # also removes extra space between fields

# insert 5 blank spaces at beginning of each line (make page offset)
awk ?{sub(/^/, ? ?);print}?

# align all text flush right on a 79-column width
awk ?{printf ?%79s\n?, $0}? file*

# center all text on a 79-character width
awk ?{l=length();s=int((79-l)/2); printf ?%?(s+l)?s\n?,$0}? file*

# substitute (find and replace) ?foo? with ?bar? on each line
awk ?{sub(/foo/,?bar?);print}? # replaces only 1st instance
gawk ?{$0=gensub(/foo/,?bar?,4);print}? # replaces only 4th instance
awk ?{gsub(/foo/,?bar?);print}? # replaces ALL instances in a line

# substitute ?foo? with ?bar? ONLY for lines which contain ?baz?
awk ?/baz/{gsub(/foo/, ?bar?)};{print}?

# substitute ?foo? with ?bar? EXCEPT for lines which contain ?baz?
awk ?!/baz/{gsub(/foo/, ?bar?)};{print}?

# change ?scarlet? or ?ruby? or ?puce? to ?red?
awk ?{gsub(/scarlet|ruby|puce/, ?red?); print}?

# reverse order of lines (emulates ?tac?)
awk ?{a[i++]=$0} END {for (j=i-1; j>=0;) print a[j?] }? file*

# if a line ends with a backslash, append the next line to it
# (fails if there are multiple lines ending with backslash?)
awk ?/\\$/ {sub(/\\$/,?"); getline t; print $0 t; next}; 1? file*

# print and sort the login names of all users
awk -F ?:? ?{ print $1 | ?sort? }? /etc/passwd

# print the first 2 fields, in opposite order, of every line
awk ?{print $2, $1}? file

# switch the first 2 fields of every line
awk ?{temp = $1; $1 = $2; $2 = temp}? file

# print every line, deleting the second field of that line
awk ?{ $2 = ??; print }?

# print in reverse order the fields of every line
awk ?{for (i=NF; i>0; i?) printf(?%s ?,i);printf (?\n?)}? file

# remove duplicate, consecutive lines (emulates ?uniq?)
awk ?a !~ $0; {a=$0}?

# remove duplicate, nonconsecutive lines
awk ?! a[$0]++? # most concise script
awk ?!($0 in a) {a[$0];print}? # most efficient script

# concatenate every 5 lines of input, using a comma separator
# between fields
awk ?ORS=%NR%5??,?:?\n?? file

SELECTIVE PRINTING OF CERTAIN LINES:

# print first 10 lines of file (emulates behavior of ?head?)
awk ?NR 1{exit};1?

# print the last 2 lines of a file (emulates ?tail -2?)
awk ?{y=x ?\n? $0; x=$0};END{print y}?

# print the last line of a file (emulates ?tail -1?)
awk ?END{print}?

# print only lines which match regular expression (emulates ?grep?)
awk ?/regex/?

# print only lines which do NOT match regex (emulates ?grep -v?)
awk ?!/regex/?

# print the line immediately before a regex, but not the line
# containing the regex
awk ?/regex/{print x};{x=$0}?
awk ?/regex/{print (x==?" ? ?match on line 1? : x)};{x=$0}?

# print the line immediately after a regex, but not the line
# containing the regex
awk ?/regex/{getline;print}?

# grep for AAA and BBB and CCC (in any order)
awk ?/AAA/; /BBB/; /CCC/?

# grep for AAA and BBB and CCC (in that order)
awk ?/AAA.*BBB.*CCC/?

# print only lines of 65 characters or longer
awk ?length > 64?

# print only lines of less than 65 characters
awk ?length