linux scripting basics

"); return 1; } } Finally, use GCC to compile the file: gcc test_exec.c-o test_exec; give it permission after the compilation is complete: chmod 777 test_exec; Then set the user tag bit: s, chmod u+s test_execTo perform the test:1. Use the root user to create a del_test file, and then switch to the normal user, the test can be deleted, and then use our command to simulate the root user to see if you can delete2. Use the root user to create a del_test file, switch to the Zhangsan user, u

Linux shell scripting:1. Program Structure Exercise: Write a script, given a positive integer, to calculate the sum of all digits of this number.For example, if the program is given input 123, it should return 1+2+3=6.2. Program Structure Exercise: Write a script, given a positive integer, to output this number in reverse order.For example: program input 123, then should output 321.3.

Linux system startup process and scripting (3)1. Special variable values${variable argument #* character} means left to right, with "character" as the delimiter, taking all strings after the first delimiter${variable argument ##* character} means left to right, with "character" as the delimiter, taking all strings following the last delimiter${variable parameter% character *} means right-to-left, with "char

to customize their command aliases and private script functions3. non-interactive shellThis is the shell used by the system to execute shell scripts.There is no command line prompt.Bash shell provides bash_env environment variables. When a non-interactive shell is started, bash_env is checked to see the startup file to be executed. If so, the shell executes the commands inside. This typically includes shell scripting variable settings.My computer doe

Overview:Overview:This section describes the array of shell scripting in Linux, advanced string processing, advanced variables, and configuring the user's environment.One, function and positional parameter extension1. TheShift command implements the jump in the position parameter, which squeezes the leftmost parameter650) this.width=650; "src=" Http://s1.51cto.com/wyfs02/M01/86/5B/wKiom1e9EFvAun-AAABG0xL4ac

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

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 always used numbers to represent the sig

login)"※ specific configuration, please see SSH certificate Login method (no password Authentication login)2. Edit the Crontab file※crontab is a command under Linux, located in/etc/crontab, used to execute the specified script at a specified time, i.e., timed to a task.If you set the script in cron.daily to execute 1:00 every day:XX 1 * * * Root run-parts/etc/cron.daily3. Edit the Automatic backup scriptPut the script in the/etc/cron.daily/directory

.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

Linux Scripting Learning D: Delete rows that match the criteria Sed ' 1,2d '/etc/fstab delete 1, 2 lines, show other rows P: The line that displays the print fit condition Sed '/^\//p '/etc/fstab matches the display, plus the original, there will be 2 duplicateSed-n '/^\//p/etc/fstab displays the line that matches the print A: Add/string after the specified line

another, or 8 seconds to exit. #d. Next, set the password for the user, first prompt the user to enter the password to be set, the password input process is not visible #e. Length detection of the password entered by the user in the previous step, if less than 5 bits (including 5-bit), prompt the user password is too short, and exit # F. For complexity detection of the password entered by the user in step D, if the input is exactly the same as a line entry in the/usr/share/dict/words dictionary

This article was translated from Isystemadmin, "List of Popular Scripting Languages for Linux and Windows."A system administrator with scripting Knowledge has a distinct distinction from other system administrators. A script is an art created by a "system administrator". This art requires knowledge of the system itself, the syntax of system administration command

Guide As we all know, system administrators need to be proficient in a scripting language, and so will the job requirements listed by the recruiting agencies. Most people think that Bash (or some other shell language) is easy to use, but some powerful languages (like Python) can bring you some other benefits. First, we'll use Python's command-line tools, and we'll touch Python's object-oriented features (the second half of this article t

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 screen View Som

In Linux systems, the two most important files for user account management are/etc/password and/etc/shadow.In the/etc/password file, each line represents an account, but there are many accounts that are system accounts. Like what:Bin, ADM, etc., as well as administrator account root. The rest is for general user accounts.Each line is composed of (to: Split):1 account name;2 password (combined with/etc/shadow);3 UID User ID, where 0 is the root, 1~499

failed_msg "Send signal SIGKILL failed ret=$ret"; return $ret; fi Ok_msg"${app} stopped by SIGKILL" Else# Delete The PID file when stop success.Rm- f ${pid_file} fiSleep 0.1return 0}# Get the status of the SRS process# @return 0 if SRS is running; otherwise, 1 for stopped.status () {Load_process_inforet=$?;if [[0 -eq $ret]]; then echo '${app} (PID ${app_pid}) is running. "; return 0; fi echo "${app} is stopped, $error _msg" return 1}menu () {case "$" inStart) Start; stop) s

[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 still in the fear of Python (though I've worked m

future in the source directory to operate the Arch/arm directory. The cross_compile is used to specify the path and prefix of the cross-compilation toolchain.(7) Cross_compile = xxx and arch = xxx and o=xxx These can be passed to the top-level makefile by command-line arguments at make.So sometimes you see someone compiling the kernel: Make O=/tmp/mykernel arch=arm cross_compile=/usr/local/arm/arm-2009q3/bin/ arm-none-linux-gnueabi-2: Link Script ana

spaces. If IFS is null, the parameters is joined without intervening separators.oldifs= "$IFS" ifs= "" array= ($result) ifs= "$oldIFS" for I in ${array[@]}; Doecho $idone# Use Facter to get a set of Key-value# Facter output has a newline character, you must replace the newline character with a space# Replace newline characters with spaces to use awk or sed# awk-v rs= "" ' {gsub ("\ n", "");p rint} '# ECHO-E "2 \n1" | Sed ': A; n;$!ba;s/\n//g 'result=$ (facter | awk '/ipaddress/!/ipaddress_lo/{p

Tags: = = Memory Pos = = = Cal Linux Ota bin percent#!/bin/shHostname= ' Hostname-s 'echo "==============hostname================"echo "Hostname= $HOSTNAME"Memoryline= ' Free | grep Mem '#字符串转数组Memoryarr= ($MEMORYLINE)echo "==============memory=================="TOTAL=${MEMORYARR[1]}USED=${MEMORYARR[2]}echo "total = $total"echo "used = $used"#计算百分比Used_pre= ' echo ' scale=2; $used *100/$total "| BC 'echo "Used_pre = $used _pre"%FREE=${MEMORYARR[3]}ech