how to write bash script

Write robust Bash scripts many people use shell scripts to complete some simple tasks and become part of their lives. Unfortunately, shell scripts are greatly affected when an exception occurs. It is necessary to minimize such problems when writing scripts. In this article, I will introduce some techniques that make bash scripts robust. How many times have you cr

Directory Part 1. Warm up Why use shell programming? Start with a sha-bang (Sha-bang refers #!) Call a script Preliminary exercises Part 2. Basics Special characters Introduction to variables and parameters Variable replacement Variable assignment Bash variables are of no type. Special variable types References (translation may be incorrect, especially quotation marks)

% Using SET-E The beginning of every script you write should contain set-e. This tells Bash that if any one of the statements returns a value that is not true, it exits bash. The advantage of using-e is to avoid making the error snowball into a serious error and catching the error as soon as possible. More re

recall that we talked about user management, rights management, and also introduced two commands, one is the install command, the other is mktemp, here we do not do more introduction.For user management, it is the allocation of the resources of the permission to their isolation.For permissions, it is the permissions that the logged-on user of the system should have assigned to the resource.So we'll cover the bash feature and the initial programming of

Always thought that in the shell script # is to represent the annotation function, also at the beginning of the script #!/bin/sh also just tell the user this is a shell script, and recently checked the next, only to find that this is not the meaning, share the following article.Transferred from: http://www.cnblogs.com/EasonJim/p/6850319.htmlFirst, meaning#!/bin/s

Read Catalogue First, everything is a string Two, references and metacharacters Three, where does the string come from, where to go Four, plus a little bit of definition, you can push to export the entire Bash scripting language syntax V. Input/Output redirection Vi. The aesthetics of the Bash scripting language: Boulevard to Jane Summarize: I confess that I once again

Sequential execution: Default rule, execution of each statement by clauseSelect execution: Branch, condition judgment, and qualified branch to execute;Loop execution: The same piece of code is repeatedly executed for a finite number of times, so the loop must have an exit condition or it will fall into a dead loop.Program code: statement and expression compositionControl statements:Bash loop control statement: for while untilFor loop:for var_name in list; DoStatement 1Statement 2...DoneLoop add

Because today wrote a small script, dead or alive unsuccessful, always reported file or directory does not exist, asked our horse classmate's normal wording, found only the difference between the script head, that is, today this article to talk about the #!/bin/sh and #!/bin/bash. This article references: https://www.cnblogs.com/aaronLinux/p/6885288.html and

To become a flexible tool, a qualified script must provide additional information to describe the role of the script, how it is executed, and where it is executed. Like the command, the script also uses parameters. Switches and parameters increase reusability, reduce costs, and save time. Positioning parameters There are three effective methods for Linux scripts

Shell script running exception in ubuntu: the difference between bash and dash I used bash to write a shell script (to be precise, I typed the script in the book into the computer). in ubuntu, use shtest. sh to run, but unexpected

Some bash scripts are not properly written. They are not written at the beginning of the file #!, But it can be executed directly. However, if you look at the kernel code, the start of the shell script's loading function will be determined. If not #! Then an error is returned:Static int load_script (struct linux_binprm * bprm, struct pt_regs * regs){...If (bprm-> Buf [0]! = '#') | (Bprm-> Buf [1]! = '! ') | (Bprm-> sh_bang ))Return-enoexec;...}Why don

=valueDeclare-i Var_name=valueDeclare a variable to be an environment variable:Export Var_name=valueDeclare-x Var_name=valueScript writing format:The first line: the Interpreter; #!/bin/bashThe absolute first line of the script is given Shebang starting at the first character position:#!bin/bashDeclare the script to be executed with bash in the bin directory, not