Shulou(Shulou.com)06/01 Report--

This article will explain in detail the sample analysis of programming and variables in Shell scripts. The editor thinks it is very practical, so I share it with you for reference. I hope you can get something after reading this article.

I. Overview of Shell scripts

II. The role of shell

three。 Write the first Shell script 1. Write a script (go to the BOOT directory, view the current location, and friendly display of all files beginning with VML in a long format) [root@localhost ~] # vim aaa.sh "arbitrarily make up an empty file with a .sh ending" / bin/bash "declaration Fixed format "one script" descriptive information can be added with or without "cd / boot/ pwdls-lh vml*~ ~ 2." Add execution permission to our script and take a look at the result [root@localhost ~] # chmod + x aaa.sh [root@localhost ~] #. / aaa.sh / / execute the script, which is our most commonly used method / boot-rwxr-xr-x. 1 root root 5.7m August 10 00:26 vmlinuz-0-rescue-cc65aecf945d4dde800fe3e29ee6edbc-rwxr-xr-x. 1 root root 5.7m August 23 2017 vmlinuz-3.10.0-693.el7.x86_643. Redirect symbol ">" pipe symbol "|" > ": redirect the command result on the left to another file or directory [root@localhost opt] # touch abc.tt abd.txt [root@localhost opt] # lsabc.tt abd.txt rh [root@localhost opt] # tar czvf test.tar.gz * .txt > test2.txt [root@localhost opt] # lsabc.tt abd.txt rh test2.txt test.tar.gz [root@localhost opt] # cat test2.txtabd.txt [root@localhost opt] #

"|": take the result of the command on the left as the processing object of the command on the right

Statistics on the occupancy of all disk partitions [root@localhost opt] # df-hT File system Type capacity available available mount point / dev/sda2 xfs 10G 3.8G 6.3G 38% / devtmpfs devtmpfs 898M 0898m 0% / devtmpfs tmpfs 912m 0912m 0% / dev/shmtmpfs tmpfs 912m 9.1m 903M1% / runtmpfs tmpfs 912M 0912M 0% / sys/fs/cgroup/dev/sdb1 xfs 20G 33M 20G 1% / mnt/sdb/dev/sda5 xfs 10G 37M 10G 1% / home/dev/sda1 xfs 6.0G 174M 5.9G 3% / boottmpfs tmpfs 183M 12K 183M 1% / run/user/42tmpfs Tmpfs 183m 0183m 0% / run/user/0 disk occupancy in the first column is in column 5 [root@localhost opt] # df-h | grep "dev/sd*" | awk'{print $1 $5}'/ dev/sda2 38% tmpfs 0%/dev/sdb1 1%/dev/sda5 1%/dev/sda1 3% [root@localhost opt] # 4. The function and type of variable

Predefined variables: the variable name acts as $0 the name of the current script $n is passed to the parameters of the script or function, n represents the number of parameters $# passed to the script or function $* all parameters passed to the script or function $@ to all parameters of the script or function $$PID$? of the current shell script process Function returns a value, or the exit status of the previous command is 5. Define a new variable and view its value

Variable name = variable value

Variable names begin with a letter or underscore and are case-sensitive

[root@localhost opt] # Producht=Python [root@localhost opt] # Version=2.7.13 [root@localhost opt] # echo $ProduchtPython [root@localhost opt] # echo $Producht $VersionPython 2.7.13 [root@localhost opt] # 6. Various quotation marks are used for assignment, and keyboard input assigns values to variables.

Please enter an integer "num1read-p", please enter the second integer "num2~ [root@localhost ~] # chmod + x c.sh [root@localhost] #. / c.sh please enter the first integer 21 please enter two integers 2327. Operation of integer variables

8. Location variable

[root@localhost ~] # vim .sss.sh

#! / bin/bashread-p "first location variable $1" read-p "second location variable $2" sum= `expr $1 + $2`echo "integer sum is $sum" ~ [root@localhost ~] #. / .sss.sh 23 45 first location variable 23 second location variable 45 integer sum 68 [root@localhost ~] #. / .sss.sh 64 120 first location variable 64 second location variable 64 The sum of 120 integers of position variables is 189. Environment variable

[root@localhost ~] # echo $PWD/root [root@localhost ~] # echo $HOME/root [root@localhost ~] # echo $USERroot [root@localhost ~] # echo $SHELL/bin/bash10. Predefined variable

#! / bin/bashread-p "first location variable $1" read-p "second location variable $2" sum= `expr $1 + $2`echo "the sum of integers is $sum" echo "script name $0" echo "detailed number $* number of" echo "parameters $#" ~ [root@localhost ~ ] #. / .sss.sh 64 120 first location variable 64 the sum of the second location variable 120 integers is 184 script name. / .sss.sh detailed number 64 120 number of parameters 2 on "sample analysis of programming and variables in Shell scripts" this article ends here Hope that the above content can be helpful to you, so that you can learn more knowledge, if you think the article is good, please share it for more people to see.

Welcome to subscribe "Shulou Technology Information " to get latest news, interesting things and hot topics in the IT industry, and controls the hottest and latest Internet news, technology news and IT industry trends.