Sed learning for application

1、 Delete centos7 System /etc/grub2.cfg All the white space characters at the beginning of the line that start with white space in the file .

# sed -nr 's/^[[:blank:]]+//p' /etc/grub2.cfg

2、 Delete /etc/fstab All # start , The first line of a line followed by at least one white space character # And white space characters .

# sed -nr 's/^#[[:blank:]]+(.*)/\1/p' /etc/fstab

3、 stay centos6 System /root/install.log Add... At the beginning of each line # Number .

# sed -nr 's/(.*)/#\1/p' /root/install.log

4、 stay /etc/fstab The document does not contain # The beginning of the first line increases # Number .

# sed -nr '/^#/!p' /etc/fstab |sed -nr 's/.*/#&/p'

# sed -nr 's/^[^#]/#/p' /etc/fstab

5、 Handle /etc/fstab route , Use sed Command to extract its directory name and base name .

# echo /etc/fstab |sed -nr 's@(^\/.*\/)(.*)@\2@p'
fstab
# echo /etc/fstab |sed -nr 's@(^\/.*\/)(.*)@\1@p'
/etc/

6、 utilize sed Take out ifconfig In the command IPv4 Address .

# ifconfig eth0 |sed -nr 's/.*inet (.*) netmask.*/\1/p'

7、 Statistics centos In the installation CD Package All under directory rpm The purpose of the document is to . The number of repetitions that separate the penultimate field

# ls *.rpm|sed -r 's@^.*\.([^.]+)\.rpm$@\1@'|sort|uniq -c

# ls *.rpm |sed -nr 's@.*\.(.*)\.rpm$@\1@p' |sort|uniq -c

8、 Statistics /etc/init.d/functions The number of occurrences of each word in the file , And sort （ use grep and sed The two methods are implemented separately ）

# grep -o '\<[a-zA-Z]\{2,\}\>' /etc/init.d/functions |sort |uniq -c |sort -nr
# sed -r 's/[^[:alpha:]]/\n/g' /etc/init.d/functions |sort |uniq -c |sort -nr

9、 Put the text file's n and n+1 The rows merge into one ,n For odd lines

# seq 10 | sed "1~2N;s/\n/ /"