Added Lab7

Lab7/regex.examples

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+grep a matches.txt # find lines containing 'a'
+grep ab matches.txt # find lines containing 'abc'
+grep '^ab$' matches.txt # find lines starting with 'abc'
+grep "[hat]" matches.txt # find lines containing h, a or t
+grep -E "[abc]{3,4}" matches.txt # find strings with 3 or 4 successive combination of a, b or c
+grep -E -n -o "[abc]{3,4}" matches.txt # show line numbers and matches only
+ip addr | egrep "([0-9]{1,3}\.){3}[0-9]{1,3}" # find IP addresses
+ip addr | egrep "([[:xdigit:]]{2}:){5}[[:xdigit:]]{2}" # find MAC Addresses 
+grep "[[:punct:]]" matches.txt # find punctuation
+grep "[linux]{3,5}" regex.examples # find l,i,n,u, or x in a pattern between 3 to 5 characters
+egrep "[linux]{3,5}" regex.examples # did it work now? 
+grep '[[:alpha:]]' regex.examples # find lettes
+fgrep '[[:alpha:]]' regex.examples # find the single quote enclosed string explicitly
+grep "[[:blank:]]" matches.txt # find space or tab
+grep "[[:space:]]" matches.txt # find all whitespace
+grep "[[:blank:]]$" matches.txt # find space or tab at the line’s end
+grep "[[:space:]]$" matches.txt # find whitespace at the line’s end
+grep -i uuid /etc/fstab # find the 'uuid' string
+sed -e 's/UUID/uuid' /etc/fstab | grep uuid # case sensitive
+sed 's/UUID/UUID UUID/' /etc/fstab | sed 's/UUID/uuid/' # replace only the first match of UUID
+sed 's/UUID/UUID UUID/' /etc/fstab | sed 's/UUID/uuid/g' # replace all matches of UUID