awk_scripts.sh

# 3697
# Syntax
awk '/pattern/ { commands }' textfile

## System variables
# FS = Field Separator (Define the separator for variables)
# NF = Number Fields (Number of fields getted by a field separator)
# RS = Record Separator (Record separator is a new line by default "\n")
# FILENAME = The name of the file that awk is reading
# BEGIN = Run command and change vars before the script
# END = Run command after script

awk 'BEGIN { FS=" "; print "START" } { print $1 } END {print NR " lines processed" }' filename
# Response
START
firstword
first
word
3 lines processed

# Count blank lines in a file
awk '/^$/ { lines += 1 } END { print lines " in this file" }' comma
# Response
3 lines in this file

# Media for students
cat students
Robert Kliebert 7 7.5 8.1 9
Louise Love 9.2 7.4 8.2 10
Carol Tiedemann 10 7.6 8.4 9.1
Thomas Lambeth 4.3 4.5 6.1 5.2
Darren Sims 5.4 7.5 7.4 7

awk '{                                                                                                                                    1 ↵
  total = $3 + $4 + $5 + $6
  avg = total / 4
  print $1 " " $2 ", " avg
} ' students
# Response
Robert Kliebert, 7.9
Louise Love, 8.7
Carol Tiedemann, 8.775
Thomas Lambeth, 5.025
Darren Sims, 6.825

# Media with media class media
awk '{
  total_of_students += 1
  total = $3 + $4 + $5 + $6
  avg = total / 4
  avg_total += avg
  print $1 " " $2 ", " avg
} END {
  avg_all = avg_total / total_of_students
  print "Total avg: " avg_all
}' students
# Response
RobertKliebert, 7.9
LouiseLove, 8.7
CarolTiedemann, 8.775
ThomasLambeth, 5.025
DarrenSims, 6.825
Total avg: 7.445

# Balance the checkbook
cat market
1000
125     market  -125.45
126     Hardware Store  -34.95
127     Video Store     -7.45
128     Book Store      -14.32
129     Gasoline        -16.10
# PS: To print a tab in terminal, press CTRL+V tab

# Create checkbook.awk with this content
# Separating by tab
BEGIN { FS = "\t" }

# Expect the first record to have the starting balance
NR == 1 { print "Beginnig Balance: \t" $1
	balance = $1
	next
}

{
	print $1, $2, $3
	print balance += $3
}
END {
	print "New balance is: " balance
}

awk -f checkbook.awk market
Beginnig Balance: 	1000
125 market -125.45
874.55
126 Hardware Store -34.95
839.6
127 Video Store -7.45
832.15
128 Book Store -14.32
817.83
129 Gasoline -16.10
801.73
New balance is: 801.73

# Print with a better format
# You can use printf in yout checkbook.awk
BEGIN { FS = "\t" }

# Expect the first record to have the starting balance
NR == 1 { print "Beginnig Balance: \t" $1
	balance = $1
	next
}

{
	printf "%10-s\t%10-s\t%10s\n", $1, $2, $3 # You must put the \n with printf
	print balance += $3
}
END {
	print "New balance is: " balance
}