Text processing 3 swordsman sed command

1. Delete the white space characters at the beginning of all lines that begin with white space in the centos7 system / etc/grub2.cfg file

 2. Delete all # and white space characters starting with # followed by at least one white space character in the / etc/fstab file

 3. Add # at the beginning of each line in the centos6 system / root/install.log

 4. Add a # sign at the beginning of a line that does not begin with # in the / etc/fstab file

 5. Process the / etc/fstab path, and use the sed command to fetch its directory name and base name

 6. Use sed to retrieve the IPv4 address of the local machine in the ifconfig command

 7. Statistics of all rpm files under the Package directory in the centos installation CD. Separate the number of repeats of the penultimate field

 8. Count and sort the number of occurrences of each word in the / etc/init.d/functions file (implemented by grep and sed respectively)

The results are so different.

Grep-o "[[: alpha:]]\ +" / etc/init.d/functions | sort | uniq-c | sort-nr

Sed-nre's / [^ [: alpha:]] + /\ nGPP'/ etc/init.d/functions | sort | uniq-c | sort-n

 9. Merge the n and next1 lines of the text file into one line, where n is an odd line