Text Processing Tools

# diff
example:
# diff <file1> <file2>

# diff -Naur <original> <updated> > patchfile
this command will created a relatively small patch

# patch 
 example:
# patch <file-need-to-patch> <patchfile>

# cut
example:
# cut -f3 -d: /etc/passwd

# /sbin/ip addr | grep 'inet' | cut -d ' ' -f6 | cut -d / -f1
this command will cut a single piece of information which is IP address from /sbin/ip addr

# head
 example
# head  /etc/passwd
 by default will display first 10 line
# head  -n  3  /etc/passwd
will display first 3 line

# tail
 example
# tail  /etc/passwd
# tail -n  3  /etc/passwd
# tail -f  /var/log/messages
this command will keep update the message log until Ctrl + c is pressed

# wc
example
# wc <file>
to count number of lines, words, bytes or character in a file

# sort
sort line

# uniq
remove duplicate line from file

# tr
# tr 'A-Z' 'a-z'
change the upper to smaller and wise visa