how to write bash script

Label: Bash script Shell is a scripting language for control systems. Bash is one of the shell interpreter and the most popular one in Linux. However, there are many shell interpreters, and each type has its own characteristics, not exactly the same .., Common shell: Sh, CSH, tcsh, Bash, KSh, Dash, zsh Co

Write a robust bash scriptMany people use shell scripts to accomplish simple tasks and become part of their lives. Unfortunately, shell scripts can be very much affected by running exceptions. It is necessary to minimize such problems when writing scripts. In this article I'll cover some of the techniques that make bash scripts robust.Using Set-u www.ahlinux.comH

Write a test script:Input Start command: test.sh, result errorThe root user is used, but the permissions are still insufficient.Input/bin/sh test.sh, you can start the script, but the syntax error:Error message The loop variable is not correct. Baidu a bit this error, explained as follows: Because Ubuntu is replacing the traditional bash with dash in order

these problems, it is great to either delete the lock file or roll back to a known state when the script encounters a problem. Fortunately, Bash provides a way to run a command or a function when bash receives a UNIX signal. You can use the Trap command. Trap command signal [signal ...] Multiple signals can be linked (lists can be obtained using kill-l), but i

Write a bash shell scriptThe script is as follows: it is used to monitor the number of mongo connections and restart the system.#! /Bin/bash# Source/etc/profileConn = '/usr/bin/mongo -- quiet Db. serverStatus (). connectionsExitEOF`Conn1 =$ {conn #*:}Curr =$ {conn1% ,*}# PID = $ (ps-ef | grep "mongodb" | grep-v grep |

Fun Bash Script: numerical calculation, bash script Numerical Calculation 6th articles The mathematical operations in Bash are not as simple as other languages, because Bash treats all variables as strings, so a = 1 + 2, a is not

must be followed by a reserved word then. You can also write them in the same line, but note that they should be separated by semicolons. These bash interpreters know that then is not part of the if condition. Otherwise, an error is reported. If Example of Writing test and [] conditions Enter a number and determine whether it is less than 100 #! /Bin/bashread-p "enter a number:" aif [$ a-lt 100] then ec

values of the shell options and positional parameters.5. Position variablesCalling parameters passed to the script from the command line in the script$, $ ... : corresponding to the command line of the 1th, 2nd ... A parameter$: Command itself$*: All parameters passed to the script, all parameters as a whole[Email protected]: All parameters passed to the

Bash script skills-trap Command, bash script-trap Share a shell script technique. When you write a shell script, you generally only ensure that the function is available, but the progr

Linux bash integrated instance bash Script Editor, linuxbash Note: This is a simple bash Script Editor, but it has been tested. The reason for writing this blog is to exercise loop control language, functions, location parameters, local variables, function parameter calls, a

Advanced Bash script, classic usage and cases, advanced bashIn linux, Bash scripts are very basic knowledge. You may feel very high when you listen to the scripts. Just like starting from the beginning, you may feel that script writing is a great tool. Although complicated scripts are very easy to understand, when we m

protected] ~]# pwd[Email protected] ~]# first.sh##/etc/fstab# Created by Anaconda on Sun June 21 02:15:00 2015## Accessible filesystems, by reference, is maintained under '/dev/disk '# See mans Pages Fstab (5), Findfs (8), mount (8) and/or Blkid (8) for more info#/dev/null: Software device, bit bucket, data black hole$?[[email protected] ~]# ID student >/dev/null[[email protected] ~]# echo $?1[[email protected] ~]# ID rhel >/dev/null[[email protected] ~]# echo $?0[Email protected] ~]#The

SHELL script strategy (learning notes) -- 1.5 bash environment configuration process, -- 1.5 bash From the perspective of user login, shell is divided into two types: Logon shell: If you log on through a terminal, use the su-username command to switch users. Non-interactive shell: for example, you can use the su username command to switch between users. Open the

Description : This is a relatively simple bash script editor, but has been tested. The reason for writing this blog is to practice the loop control language, functions, positional parameters, local variables, and function parameter calls, as well as calls between functions, as well as parameters for obtaining user options and options.Note: The script options and

Bash script exercises and bash scripts Exercise 1: 1. Add five users, user1,..., user5; 2. The password of each user is the same as the user name. After the password is added, the command execution result is not displayed; 3. After each user is added, it must be displayed that the user has been added successfully. Useradd user1 Echo "user1" | passwd -- stdi

- RMInfo.txt - - Echo "Unzip done." in -#此时在/a folder appears under program tojdk_dir=$ (EchoJdk*.*.*_*) + - CD the *Java_home="java_home=/program/$JDK _dir" $ Panax NotoginsengClasspath='classpath=.: $JAVA _home/lib/dt.jar: $JAVA _home/lib/tools.jar' - theGlobel_path='path= $JAVA _home/bin: $PATH' + A Echo "">>./. Bash_profile the Echo "#Set Java Runtime Environment">>./. Bash_profile + Echo "">>./. Bash_profile - Echo$JAVA _home >>.. Bash_profile $ Echo$CLASSPATH >>./. Bash_profile $ Ec

@ 2013/7/19 -Added the bashmap_clear command to delete the key or clear the entire map.Step 1: add the function to the bash script (or. bashrc) # for bashmap {# echo md5 code for $1md5(){ if [ X"$1" == X"" ] then echo "" else echo "$1" | md5sum - | cut -c 1-32 fi}# Usage# > bashmap "key" "value" # set map[key] = value.# > bashmap "key" # print map[key]bashmap(){ WX_BASHMAP_PREFIX="

@2013/7/19 -Add the bashmap_clear command to delete the key or empty the entire map. Step 1: Add the function to the bash script (or. bashrc) # for Bashmap {# echo MD5 code for $ MD5 () {if [x "$ = = X"] then echo "" Else echo "| Md5sum-| Cut-c 1-32 fi} # Usage # > Bashmap "Key" "Value" # set Map[key] = value. # > Bashmap "key" # Print Map[key] Bashmap () {wx_bashmap_prefix= "BASHMAP_" Export Wx_bashmap

Description : This is a relatively simple bash script editor, but has been tested. The reason for writing this blog is to practice the loop control language, functions, positional parameters, local variables, and function parameter calls, as well as calls between functions, as well as parameters for obtaining user options and options.Note: The script options and

Sometimes you write scripts with errors that are listed like headings, mostly because your script files are edited under Windows. Windows, the end of each line is \n\r, and in Linux under the end of the file is \ n, then you edit the file in Windows under Linux open to see the end of each line will be more than one character \ r, Cat-a Urfile you can see this \ The r character is displayed as a ^m, and it i