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awk_Notes.txt
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awk_Notes.txt
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---------
AWK Notes
---------
awk '$4 ~/Technology/'
-
awk '$1 >200'
-
awk '{print $2,$NF;}'
-
awk '/Thomas/
/Nisha/'
-
awk 'BEGIN { count=0;}
$4 ~ /Technology/ { count++; }
END { print "Number of employees in Technology Dept =",count;}'
-
awk -f script-filename inputfilename
BEGIN {
total=0;
}
{
itemno=$1;
book=$2;
bookamount=$3*$4;
total=total+bookamount;
print itemno," ", book,"\t","$"bookamount;
}
END {
print "Total Amount = $"total;
}
-
$cat student.awk
BEGIN {
test1=0;
test2=0;
test3=0;
print "Name\tRollNo\t Average Score";
}
{
total=$3+$4+$5;
test1=test1+$3;
test2=test2+$4;
test3=test3+$5;
print $1"\t"$2"\t",total/3;
}
END {
print "Average of Test1="test1/NR;
print "Average of Test2="test2/NR;
print "Average of Test3="test3/NR;
}
-
$ cat string.awk
BEGIN{
title="AWK";
print "<html>\n<title>"title"</title><body bgcolor=\"#ffffff\">\n<table border=1><th colspan=2 align=centre>Student Details</th>";
}
{
name=$1;
rollno=$2;
print "<tr><td>"name"</td><td>"rollno"</td></tr>";
}
END {
print "</table></body>\n</html>";
}
<html>
<title>AWK</title><body bgcolor="#ffffff">
<table border=1><th colspan=2 align=centre>Student Details</th>
<tr><td>Jones</td><td>2143</td></tr>
<tr><td>Gondrol</td><td>2321</td></tr>
<tr><td>RinRao</td><td>2122</td></tr>
<tr><td>Edwin</td><td>2537</td></tr>
<tr><td>Dayan</td><td>2415</td></tr>
</table></body>
</html>
-
8 Powerful Awk Built-in Variables – FS, OFS, RS, ORS, NR, NF, FILENAME, FNR
-
awk -F 'FS' 'commands' inputfilename
(or)
awk 'BEGIN{FS="FS";}'
-
BEGIN{
FS=":";
print "Name\tUserID\tGroupID\tHomeDirectory";
}
{
print $1"\t"$3"\t"$4"\t"$6;
}
END {
print NR,"Records Processed";
}
-
awk -F':' '{print $3,$4;}' /etc/passwd
-
awk -F':' 'BEGIN{OFS="=";} {print $3,$4;}' /etc/passwd
-
BEGIN {
RS="\n\n";
FS="\n";
}
{
print $1,$2;
}
-
awk 'BEGIN{ORS="=";} {print;}'
-
awk '{print "Processing Record - ",NR;}END {print NR, "Students Records are processed";}
-
awk '{print NR,"->",NF}'
-
awk '{print FILENAME}'
-
awk '{print FILENAME, FNR;}'
-
awk -F ':' '$5 == "" '
-
awk -F ':' '$3>=100 && $NF ~ /\/bin\/sh/'
-
awk -F ':' '$3==$4'
-
awk 'NR % 2 == 0' # print even-numbered lines
-
awk -F ':' '$3 > maxuid { maxuid=$3; maxline=$0 }; END { print maxuid, maxline }'
-
awk -F ':' '$NF ~ /\/bin\/sh/ { n++ }; END { print n }' /etc/passwd
-
awk -F ':' '{ total += NF }; END { print total }'
-
Operator Description
~ Match operator
!~ No Match operator
> Is greater than
>= Is greater than or equal to
< Is less than
<= Is less than or equal to
<= Is less than or equal to
== Is equal to
!= Is not equal to
&& Both the conditional expression should be true
|| Any one of the conditional expression should be true
= Assignment
+= Shortcut addition assignment
-= Shortcut subtraction assignment
*= Shortcut multiplication assignment
/= Shortcut division assignment
%= Shortcut modulo division assignment
+ Addition
- Subtraction
* Multiplication
/ Division
% Modulo Division
+ Positivate the number
- Negate the number
++ AutoIncrement
– AutoDecrement
-----------------------------
awk '{
if ($3 =="" || $4 == "" || $5 == "")
print "Some score for the student",$1,"is missing";'
}' student-marks
----------------
awk '{
if ($3 >=35 && $4 >= 35 && $5 >= 35)
print $0,"=>","Pass";
else
print $0,"=>","Fail";
}' student-marks
---------------
if(conditional-expression1)
action1;
else if(conditional-expression2)
action2;
else if(conditional-expression3)
action3;
.
.
else
action n;
-----------
cat grade.awk
{
total=$3+$4+$5;
avg=total/3;
if ( avg >= 90 ) grade="A";
else if ( avg >= 80) grade ="B";
else if (avg >= 70) grade ="C";
else grade="D";
print $0,"=>",grade;
}
---------------
conditional-expression ? action1 : action2 ;
awk 'ORS=NR%3?",":"\n"' student-marks
-------------
$awk 'BEGIN { while (count++<50) string=string "x"; print string }'
xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx
--------------
$ awk 'BEGIN{
count=1;
do
print "This gets printed at least once";
while(count!=1)
}'
This gets printed at least once
-------------
$ awk '{ for (i = 1; i <= NF; i++) total = total+$i }; END { print total }'
12 23 34 45 56
34 56 23 45 23
351
--------
$ awk 'BEGIN{
x=1;
while(1)
{
print "Iteration";
if ( x==3 )
break;
x++;
}}'
Iteration
Iteration
Iteration
--------------------
$ awk 'BEGIN{
x=1;
while(x<=10)
{
if(x==5){
x++;
continue;
}
print "Value of x",x;x++;
}
}'
Value of x 1
Value of x 2
Value of x 3
Value of x 4
Value of x 6
Value of x 7
Value of x 8
Value of x 9
Value of x 10
-----------------
$ awk 'BEGIN{
x=1;
while(x<=10)
{
if(x==5){
exit 2;}
print "Value of x",x;x++;
}
}'
Value of x 1
Value of x 2
Value of x 3
Value of x 4
---
echo $? = 2 ===========================
awk and sed tips and tricks
===========================
awk - (gawk) pattern scanning and processing language
# www.gnu.org/software/gawk/manual/gawk.html
--------------------
awk '$4 ~/Technology/'
-
awk '$1 >200'
-
awk '{print $2,$NF;}'
-
awk '/Thomas/
/Nisha/'
-
awk 'BEGIN { count=0;}
$4 ~ /Technology/ { count++; }
END { print "Number of employees in Technology Dept =",count;}'
-
awk -f script-filename inputfilename
BEGIN {
total=0;
}
{
itemno=$1;
book=$2;
bookamount=$3*$4;
total=total+bookamount;
print itemno," ", book,"\t","$"bookamount;
}
END {
print "Total Amount = $"total;
}
-
$cat student.awk
BEGIN {
test1=0;
test2=0;
test3=0;
print "Name\tRollNo\t Average Score";
}
{
total=$3+$4+$5;
test1=test1+$3;
test2=test2+$4;
test3=test3+$5;
print $1"\t"$2"\t",total/3;
}
END {
print "Average of Test1="test1/NR;
print "Average of Test2="test2/NR;
print "Average of Test3="test3/NR;
}
-
$ cat string.awk
BEGIN{
title="AWK";
print "<html>\n<title>"title"</title><body bgcolor=\"#ffffff\">\n<table border=1><th colspan=2 align=centre>Student Details</th>";
}
{
name=$1;
rollno=$2;
print "<tr><td>"name"</td><td>"rollno"</td></tr>";
}
END {
print "</table></body>\n</html>";
}
<html>
<title>AWK</title><body bgcolor="#ffffff">
<table border=1><th colspan=2 align=centre>Student Details</th>
<tr><td>Jones</td><td>2143</td></tr>
<tr><td>Gondrol</td><td>2321</td></tr>
<tr><td>RinRao</td><td>2122</td></tr>
<tr><td>Edwin</td><td>2537</td></tr>
<tr><td>Dayan</td><td>2415</td></tr>
</table></body>
</html>
-
8 Powerful Awk Built-in Variables – FS, OFS, RS, ORS, NR, NF, FILENAME, FNR
-
awk -F 'FS' 'commands' inputfilename
(or)
awk 'BEGIN{FS="FS";}'
-
BEGIN{
FS=":";
print "Name\tUserID\tGroupID\tHomeDirectory";
}
{
print $1"\t"$3"\t"$4"\t"$6;
}
END {
print NR,"Records Processed";
}
-
awk -F':' '{print $3,$4;}' /etc/passwd
-
awk -F':' 'BEGIN{OFS="=";} {print $3,$4;}' /etc/passwd
-
BEGIN {
RS="\n\n";
FS="\n";
}
{
print $1,$2;
}
-
awk 'BEGIN{ORS="=";} {print;}'
-
awk '{print "Processing Record - ",NR;}END {print NR, "Students Records are processed";}
-
awk '{print NR,"->",NF}'
-
awk '{print FILENAME}'
-
awk '{print FILENAME, FNR;}'
-
awk -F ':' '$5 == "" '
-
awk -F ':' '$3>=100 && $NF ~ /\/bin\/sh/'
-
awk -F ':' '$3==$4'
-
awk 'NR % 2 == 0' # print even-numbered lines
-
awk -F ':' '$3 > maxuid { maxuid=$3; maxline=$0 }; END { print maxuid, maxline }'
-
awk -F ':' '$NF ~ /\/bin\/sh/ { n++ }; END { print n }' /etc/passwd
-
awk -F ':' '{ total += NF }; END { print total }'
-
Operator Description
~ Match operator
!~ No Match operator
> Is greater than
>= Is greater than or equal to
< Is less than
<= Is less than or equal to
<= Is less than or equal to
== Is equal to
!= Is not equal to
&& Both the conditional expression should be true
|| Any one of the conditional expression should be true
= Assignment
+= Shortcut addition assignment
-= Shortcut subtraction assignment
*= Shortcut multiplication assignment
/= Shortcut division assignment
%= Shortcut modulo division assignment
+ Addition
- Subtraction
* Multiplication
/ Division
% Modulo Division
+ Positivate the number
- Negate the number
++ AutoIncrement
– AutoDecrement
-----------------------------
awk '{
if ($3 =="" || $4 == "" || $5 == "")
print "Some score for the student",$1,"is missing";'
}' student-marks
----------------
awk '{
if ($3 >=35 && $4 >= 35 && $5 >= 35)
print $0,"=>","Pass";
else
print $0,"=>","Fail";
}' student-marks
---------------
if(conditional-expression1)
action1;
else if(conditional-expression2)
action2;
else if(conditional-expression3)
action3;
.
.
else
action n;
-----------
cat grade.awk
{
total=$3+$4+$5;
avg=total/3;
if ( avg >= 90 ) grade="A";
else if ( avg >= 80) grade ="B";
else if (avg >= 70) grade ="C";
else grade="D";
print $0,"=>",grade;
}
---------------
conditional-expression ? action1 : action2 ;
awk 'ORS=NR%3?",":"\n"' student-marks
-------------
$awk 'BEGIN { while (count++<50) string=string "x"; print string }'
xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx
--------------
$ awk 'BEGIN{
count=1;
do
print "This gets printed at least once";
while(count!=1)
}'
This gets printed at least once
-------------
$ awk '{ for (i = 1; i <= NF; i++) total = total+$i }; END { print total }'
12 23 34 45 56
34 56 23 45 23
351
--------
$ awk 'BEGIN{
x=1;
while(1)
{
print "Iteration";
if ( x==3 )
break;
x++;
}}'
Iteration
Iteration
Iteration
--------------------
$ awk 'BEGIN{
x=1;
while(x<=10)
{
if(x==5){
x++;
continue;
}
print "Value of x",x;x++;
}
}'
Value of x 1
Value of x 2
Value of x 3
Value of x 4
Value of x 6
Value of x 7
Value of x 8
Value of x 9
Value of x 10
-----------------
$ awk 'BEGIN{
x=1;
while(x<=10)
{
if(x==5){
exit 2;}
print "Value of x",x;x++;
}
}'
Value of x 1
Value of x 2
Value of x 3
Value of x 4
---
echo $? = 2
----------------------------
sed - stream editor
# sed "/'\/'${user}' '/d" /etc/exports ">" /tmp/exports.new
# sed -e ${lineno}s:$srcsrv:$DSTSRV: -e ${lineno}s:$uhomedir:$DSTDIR/$user: /etc/auto.eshome ">" /tmp/auto.eshome.new
# sed -e ${lineno}s:$srcsrv:${DSTSRV}-'\$'NET: -e ${lineno}s:$uhomedir:$DSTDIR/$user: /etc/auto.eshome ">" /tmp/auto.eshome.new
# sed -e ${lineno}s:${srcsrv}-'\$'NET:$DSTSRV: -e ${lineno}s:$uhomedir:$DSTDIR/$user: /etc/auto.eshome ">" /tmp/auto.eshome.new
# sed -e ${lineno}s:$srcsrv:$DSTSRV: -e ${lineno}s:$uhomedir:$DSTDIR/$user: /etc/auto.eshome ">" /tmp/auto.eshome.new
# sed "1,/$month.*$lastyear$/d" $LOGFILE | sed "1,/^========/d" > $LOGFILE.new
# sed -n 1,${lineno}p $NISDIR/$file2edit > $pwtop
# sed -n ${lineno},\$p $NISDIR/$file2edit > $pwbot
---------------
sed 's/:\$1\$.\{31\}:/:xxxxxxxxxx:/g' shadow > shadow.new
awk -F: '{print $1,"xxxxxxxxxx",$3,$4,$5,$6,$7,$8,$9}' OFS=":" shadow > shadow.new
tags: AWK