Shell (3): awk (2) .......

#From E. Quigley book
#To print all lines containing the pattern
awk '/pattern/' file

#To print the lines starting with the regex pattern1 and pattern2
awk '/^ (pattern1|pattern2)/' file

#To print the field  1 of  lines starting with the regex pattern1 
awk '/^ [pattern1]/{print $1}' file

#To print field 1 (or multiple fields, in particular orders)
awk '{ print $1}' file
awk '{ print $1, $2, $3}' file
awk '{ print $3, $2, $1}' file

#To print field 1 and 2 if the pattern is present
awk '/pattern/{ print $1, $2}' file

#To print the lines starting with the regex
awk '/^ pattern/{ print "Hello!"}' file

#Print entire file (with row number, with field number)
awk  '{ print }' file
awk  '{ print $0}' file
awk  '{ print NR, $0}' file
awk  '{ print NF, $0}' file

#Piping a command to awk
df | awk '$1  > 50000'
date | awk '{ print "Month: $2 "\nYear: " , $6}'

#Using escape sequence
awk '/pattern/ { print "\t\tHave a good day,  "$1, $2 "\!"}' file
awk '/pattern/ { print "Hello there,  "$1}' file

#Using OFMT variable to format decimal values
awk 'BEGIN{ OFMT ="%.2f" ; print 1.348973, 12E-2}' file

#Using prinf for fancy output (here spacing)
 awk {printf  "The name is:  %10s  ID is %8d\n", $1, $3}'  file


#Changing field separator (-F is used to reassign the value of the separator) (here colon is separator)
awk -F:  '{ print $1}' file
awk -F"[ :]" '{ print $1, $2}' file
awk -F:  '/pattern/'{ print $1, $2}' file

#Print if $3 is less than 5000
awk  '$3 < 5000' file

#Print lines starting with an uppercase letter, followed by smaller case letters, followed by space
awk  '/^[A-Z][a-z]+ /' file

#Print lines with the patterns
awk  '$1 ~ /[Dd]oll/' file

#Print lines without the pattern at the end
awk  '$1 !~ /pattern$/' file

POSIX
#Print lines with bracketed characters added by POSIX
awk  '$1 ~ /[[:lower:]]+g[[:space:]]+g[[:digit:]]/' file

#Print lines if column $3 has a literal period followed by number between the given range

awk  '$3 ~ / \.[2-6]+/' file

#Print $1 and $2 of lines if column $5 does not have the pattern

awk  '$5 !~ /pattern/{print $1, $2}' file

#Print $1 if line starts with the pattern and then add a string

awk  '$1 ~ /^pattern/{print $1 "How are you?"} file

#Print $4 if ends with three digits

awk  '$4 ~ /[0-9][0-9]/{print $4}'  file

#Print string and a field $4  if $3 ends with  a pattern

awk  '$3 ~ /pattern$/{print "I paid" $4 "for this book"}'  file

#If the line has the pattern, add 5 (subtract 4, divide by 2) to its third column and print the line

awk  '/pattern/{print $3+ 5}' file
awk  '/pattern/{print $3 - 4}' file
awk  '/pattern/{print $3 / 2}' file

COMPARISONS (==, >, =>,<, <=,  )
#Print line if  $3 is exactly the given value (comparisons)

awk  '$3 == 5360'  file
awk  '$3 > 5000{print $1}'  file
awk  '$2 <= 23{print $3}'  file
awk  '!($1 ==10) {print $5}'  file

#If $1 is greater than $2, assign $1 to max; If $2 is greater than $1, assign $2 to max; (comparisons)

awk  '{max=($1 > $2) ? $1 :  $2; print max}'  file
awk  '{print ($5 > 3 ? "High " $5  : "Low " $5)}'  file

#Multiplies $3 and $4 and if the result is more than 5000, prints the lines (comparisons)

awk  '$3 * $4 > 5000'  file


LOGICAL OPEARTORS (&&, ||)
#Prints lines if both conditions are met i.e $2 is more than 10 and less than 20
awk  '$2 > 10  &&  $2 <= 20'  file

#Prints lines if both conditions are not met
awk  '! ($2 > 10  &&  $2 <= 20)'  file

#Prints lines if any of the conditions are met i.e $2 is more than 10 and less than 20
awk  '$2 == 20  ||  $2 <= 20'  file

#Prints lines if any of the conditions are met 
awk  '$2 == "pattern"  ||  $1 ~ /pattern1/ {print $1, $2}'  file


#Prints lines between first occurrence of pattern1 and pattern2 (range patterns)
awk  '/pattern1/, /pattern2/' file
awk  '/^pattern1/, /^pattern2/' file

# If $2 starts with the specified pattern, add .5 to $5 and print it, also print $3
awk '$2 ~ /^pattern/ \
{print  "Percentage: "$5 + .5  "Volume: "$3}'  file