AWK
Print the length of the longest input line:
awk '{if (length($0) > max) max = length($0) } END { print max}' data

Print every line longer than 80 characters:
awk 'length($0) > 80' data

Print the length of the longest line in data:
expand data | awk '{if (x < length()) x = length() } END { print "maximum line length is " x}'

Print every line that has at least one field
awk 'NF > 0' data

Print seven random number from 0 to 100 inclusive
awk 'BEGIN{ for (i = 1; i <= 7; i++) print int(101 * rand()) }'

Print the total number of bytes used by files
ls -l files | awk '{ x += $5 } END { print "total bytes: " x }'

Print a sorted list of login names of all users
awk -F: '{ print $1 }' /etc/passwd | sort

Count lines in a file
awk 'END { print NR}' data

Print root mean square deviation
awk '{ x += ($1-$2)^2}{print (x/NR)^0.5}' data

Print formated
awk '/Search/{printf("%14.8f %14.8f\n",($3*4),($4*2))}'

Print an increasing number up to 60
awk 'BEGIN { for ( i=1 ; i <= 60 ; i++ ) print i, 1, 1, 0 }'

Print sum of two numbers in same line together with complete line
echo 3 4 | awk '{ for (i=1; i<=NF;i++) xyz = xyz + $i} END {print xyz,$0}'

Print running average of first colum
awk '{ x += $1}{print (x/NR)}' data

Print first some headings, then $1 in list.dat as a string of 10 characters that are left-justified. 
awk 'BEGIN { printf "%-10s %s\n", "Name", "Number"} { printf "%-10s %s\n", $1, $2 }' list.dat

printf "%d", 99/2	49
printf "%e", 99/2	4.950000e+01
printf "%f", 99/2	49.500000
printf "%6.2f", 99/2	49.50
printf "%g", 99/2	49.5
printf "%o", 99	143
printf "%06o", 99	000143
printf "%x", 99	63
printf "|%s|", "January"	|January|
printf "|%10s|", "January"	|   January|
printf "|%-10s|", "January"	|January   |
printf "|%.3s|", "January"	|Jan|
printf "|%10.3s|", "January"	| Jan|
printf "|%-10.3s|", "January"	|Jan |
printf "%%"	%


SED
deletes everything in between colon and {
grep -n "{" file-name | sed 's/*:.*/:/; s/.*{*/{/'

replaces pattern by set of variables
sed 's/10 10 10/'"$cell $cell $cell"'/' file-name

MERGE multiple PDFs into one file
gs -dNOPAUSE -sDEVICE=pdfwrite -sOUTPUTFILE=firstANDsecond.pdf -dBATCH first.pdf second.pdf

backup dir1 into dir2
rsync -avz dir1 dir2