linux shell scripting tutorial for beginners

echo "Top Ten Disk Space Usage" echo "for $CHECK _directories Directory" For Dir_check in $CHECK _directories Do echo "" echo "The $DIR _check Directory:" Du-s $DIR _check 2>/dev/null | Sort-rn | Sed ' {one, $D; =} ' | Sed ' N; s/\n//' | Gawk ' {printf $ ': "\ T" $ "t" $ "\ n"} ' Done Exit [Email protected]:~/shell/24zhang$ Run:./big_user.shOnly two directories/var/log/home are specified above, and the generated rep

1. Linux Scripting Basics1.1 Basic Introduction to grammar1.1.1 StartThe program must start with the following line (must be placed on the first line of the file):#!/bin/shThe symbolic #! is used to tell the system that the parameters behind it are the programs used to execute the file. In this example we use/BIN/SH to execute the program.When you edit a good script, you must also make it executable if you

Basics of Linux Shell scripting here we first talk about the shell of the basic syntax, the beginning, comments, variables and environment variables, to do a basic introduction, although not related to specific things, but lay the foundation is to learn easily after the premise. 1.

command. You can use Echo to print any variable value in any place where you suspect it is wrong. That's why most shell programmers spend 80% of their time debugging programs. of the Shell programThe advantage is that there is no need to recompile, and it does not take much time to insert an echo command.The shell also has a real debug mode. If there is an error

2017 09:48:22 +0800from localhost [127.0.0.1]-----The following addresses had permanent fatal errors-----[email protected]>(reason:550 Failed to connect remote host.)-----Transcript of Session follows-----... while talking to mx3.qq.com.:... while talking to mx2.qq.com.:So the machine was restarted a bit. You can do it.[Email protected]:/var/mail$ Echo]20171204tete" | Mail-s "TEst2"Xcy[Email protected]:/var/mail$ Mail"/var/mail/xcy": 3 messages 1 new 2 unreadU 1 Mail Delivery Subs December 4 10

be output to the monitor while redirecting files, but generally overwrite the original file content, you can use the-a append contentCode 5-23[Email protected]:/data# date | Tee Textmon Dec 5 06:18:04 CST 2016[email protected]:/data# cat text Mon Dec 5 06:18:04 CST 2016[email protected]: /data# who | Tee text root pts/0 2016-12-05 04:26 (122.90.143.21) [email protected]:/data# cat text root pts/0 2016-12-05 04:26 (122.90.143.21) [Email protected]:/data# date | Tee-a text

[Turn]http://www.knktc.com/2011/08/20/linux-shell-expect%e6%89%b9%e9%87%8fscp%e8%84%9a%e6%9c%ac%e5%b7%a5%e5%85%b7/ One of the most recent tasks in preparing a deployment is to send some files, such as installation packages, to a large number of servers. Although there is already a Brother Woo script available: A Python script written by the SSH and SCP features provided by the Paramiko module. But I'm stil

used with variable names, and if the loop body does not include a variable name, a dead loop may occurHow the list is generated:1) Give a direct2) List of pure integersSEQ: Output An integer listseq [First [INCREMENT]] Last3) curly braces unfold{first.. Last}4) return value of the execution result of the command5) GLOBBING6) references to certain variables: [email protected], $*Features of the For loop:1. There is almost no cycle of death;2. The entire list needs to be loaded into memory during

results of "mail.jpg tux.jpg".quotation marks (single and double quotation marks) prevent this wildcard extension: #!/bin/shecho "*.jpg" Echo ' *.jpg ' This will print "*.jpg" two times.Single quotes are more restrictive. It prevents any variable expansion. Double quotes prevent wildcard expansion but allow variable expansion. #!/bin/shecho $SHELLecho "$SHELL" Echo ' $SHELL ' The result of the operation is

.2) read uses the IFS character to parse the text, and here we specify the IFS as a comma.Cat >> $outfile This includes an output append redirect (>>) and an input append redirect (>> appends the output of the cat command to the file specified by the $outfile variable.The input to the Cat command is not taken from standard input, but is redirected to the data stored in the script.The EOF symbol marks the beginning and end of the data appended to the file.Input file + run + Result:DescriptionSpe

specified shell command V Start the VI editor with the current file . Repeat the previous command N Find in file the overflow matches the content of the specified expression ‘ Jumps to the first content that the specified expression matches to Ctrl+l Redraw the current scre

TopicShell Scripting Knowledge points: What are trap signals in Linux system scripts and how are they used?Reference answer: "Trap signal Command description"The trap command is used to specify the actions to be taken after a signal is received, and a common use of the trap command is to complete the cleanup work when the script is interrupted.Historically, the shell