Stampa  

 

# begin printing text
# \n stands for new line
server01:/# awk 'BEGIN { print " one \n two\n three" }'
 one 
 two
 three
 

# \t stands for tab 
awk 'BEGIN { print "one\t two \tthree" }'
one      two    three

# use following syntax to print single quote(1)
server01:/#awk 'BEGIN { print "Print single quote: \t  '\'' " }'
Print single quote:       '

# in alternative, use following syntax to print single quote(1) alternative
server01:/#awk "BEGIN { print \" Print single quote: \t ' \" }"
 Print single quote:     '

# print double quotes \42 (1)
server01:/#awk 'BEGIN { print "Print double quote: \42" }'
Print double quote: "


# print double quotes (2) alternative, declaring it first.
server01:/#awk -v db="\"" 'BEGIN { print "Here is a single quote " db  " " }'

# formatting output 
server01:/#ls -la | awk 'BEGIN   { print "File\tOwner\tBytes" } { print $9, "\t", $3  "\t", $5 } END     { print " - DONE -" } '

File    Owner   Bytes
                 
./       bin     8192
../      root    8192
backup/          root    8192
boot.sys/        bin     96
bootconf         root    21
bootfs@          root    14
current/         root    8192
ioconfig         root    3804
kernrel          root    82
krs/     root    96

# loop basic example
server01:/# awk  'BEGIN { for (i=1; i <= 5; i++) {print "The square of " i " is " i*i  ;} }  '

The square of 1 is 1
The square of 2 is 4
The square of 3 is 9
The square of 4 is 16
The square of 5 is 25

# working with text files
# text file example "testfile.txt"
# columns (or fields) are separated by blank

ITALY ROME PARIOLI
ITALY MILAN
FRANCE PARIS
FRANCE LION
ITALY ROME ALBERONE
ITALY PALERMO BRANCACCIO
SPAIN MADRID
USA NY QUEEN ASTORIA
PORTUGAL LISBON

# print fields (1)
# $0 to print all text file row 
server01:/#awk '{print $0}' testfile.txt 

ITALY ROME PARIOLI
ITALY MILAN
FRANCE PARIS
FRANCE LION
ITALY ROME ALBERONE
ITALY PALERMO BRANCACCIO
SPAIN MADRID
USA NY QUEEN ASTORIA
PORTUGAL LISBON

# print fields (2)
# first e third column and using string converting case  tolower or  toupper
server01:/#awk ' {print $1 ,  tolower($3)} ' testfile.txt 

ITALY parioli
ITALY 
FRANCE 
FRANCE 
ITALY alberone
ITALY brancaccio
SPAIN 
USA queen
PORTUGAL

# managing fields,  NF identify their number 
server01:/#awk '{print $0 , "Number field:\t" NF }' testfile.txt

ITALY ROME PARIOLI Number field:        3
ITALY MILAN Number field:       2
FRANCE PARIS Number field:      2
FRANCE LION Number field:       2
ITALY ROME ALBERONE Number field:       3
ITALY PALERMO BRANCACCIO Number field:  3
SPAIN MADRID Number field:      2
USA NY QUEEN ASTORIA Number field:      4
PORTUGAL LISBON Number field:   2

# columns separated by chars
# columns separated by : in file cityresidents.txt:

Firenze:979945
Bologna:968400
Padova:913174
Verona:899603
Caserta:899248
Genova:883913
Firenze:979945
Bologna:968400
Padova:913174
Verona:899603
Caserta:899248
Genova:883913

# if fields are non separated spaces but by  some chars,  –F to define separation
server01:/#awk  -F":"  '{print "City: " $1 "\t Residents: " $2}' cityresidents.txt 

City: Firenze    Residents: 979945
City: Bologna    Residents: 968400
City: Padova     Residents: 913174
City: Verona     Residents: 899603
City: Caserta    Residents: 899248
City: Genova     Residents: 883913
City: Firenze    Residents: 979945
City: Bologna    Residents: 968400
City: Padova     Residents: 913174
City: Verona     Residents: 899603
City: Caserta    Residents: 899248
City: Genova     Residents: 883913

# NRidentify row number in text file
server01:/#awk '{ print "ROW: "NR "\t" $0}' testfile.txt

ROW: 1  ITALY ROME PARIOLI
ROW: 2  ITALY MILAN
ROW: 3  FRANCE PARIS
ROW: 4  FRANCE LION
ROW: 5  ITALY ROME ALBERONE
ROW: 6  ITALY PALERMO BRANCACCIO
ROW: 7  SPAIN MADRID
ROW: 8  USA NY QUEEN ASTORIA
ROW: 9  PORTUGAL LISBON

# use sort -u command to eliminate duplicate rows 
server01:/#awk ' {print $1 , tolower($3)} ' testfile.txt |sort -u
 

FRANCE 
ITALY 
ITALY alberone
ITALY brancaccio
ITALY parioli
PORTUGAL 
SPAIN 

# adding and encapsuling chars to field 
server01:/#awk '{ printf("*%s (%s)\n", tolower($2), toupper($1)) }' testfile.txt
 

*rome (ITALY)
*milan (ITALY)
*paris (FRANCE)
*lion (FRANCE)
*rome (ITALY)
*palermo (ITALY)
*madrid (SPAIN)
*ny (USA)
*lisbon (PORTUGAL)

# if, conditional (1)
# if first field equals to ITALY print line
server01:/#awk ' ($1=="ITALY") {print $0}' testfile.txt 
 

ITALY ROME PARIOLI
ITALY MILAN
ITALY ROME ALBERONE
ITALY PALERMO BRANCACCIO

# if, conditional (2)
# use of match if first field contains (match) IT print row
server01:/#awk 'match($1,"IT") {print $0}' testfile.txt 
 

ITALY ROME PARIOLI
ITALY MILAN
ITALY ROME ALBERONE
ITALY PALERMO BRANCACCIO

# if, conditional (3) compact construct, if row contains "ROME" print it
server01:/#awk '$0 ~ /ROME/ {print $0}' testfile.txt 
 

ITALY ROME PARIOLI
ITALY ROME ALBERONE

#extract, using substr, chars from String by position, in the example from 1 to 2 position of first column
server01:/#awk '{ print substr($1,1,2)}' testfile.txt
 

IT
IT
FR
FR
IT
IT
SP
US
PO

# function index(s1,s2)  returns position of parameter in the string
server01:/#awk '{ print index($0,"ROME")}' testfile.txt
 

7
0
0
0
7
0
0
0
0
	
# function length returs string  length
server01:/#awk '{ print "Row:" NR  "\t" "Field string: "  $2 "\t"  "String length: "   length($2)}' testfile.txt

Row:1   Field string: ROME      String length: 4
Row:2   Field string: MILAN     String length: 5
Row:3   Field string: PARIS     String length: 5
Row:4   Field string: LION      String length: 4
Row:5   Field string: ROME      String length: 4
Row:6   Field string: PALERMO   String length: 7
Row:7   Field string: MADRID    String length: 6
Row:8   Field string: NY        String length: 2
Row:9   Field string: LISBON    String length: 6
	
#length conditional construct. If field 2 is more the 5 chars, print it
server01:/#awk '(length($2)>5) {print $2}' testfile.txt 

PALERMO
MADRID
LISBON

Marco Magnani marcomagnani@fishscript.com