bash shell scripting tutorial

contains the information and location of the source file. Referencing a hard-link file is equivalent to referencing a source fileCp-l test1 test4The-l parameter creates a hard-link test4 that points to the file test1.Note: You can only create hard links between files on the same storage media, and you cannot create hard links between files under different mount points.The parameter-s creates a symbolic link, or a soft connectionCp-s Test TEST5When copying a linked file, be aware that if you use

What is Bash shell script programming?A: There are multiple shells in Linux, and the default shell for CentOS and Redhat is the bash shell. As for shell scripts, this is a bit like (. bat file) for batch files inside the Windows o

Bash shell scripting Getting Started (iii) cycleWhat is loop execution?To run a code segment repeatedly multiple timesHow many times to run repeatedly:Number of cycles known beforehandNumber of cycles unknown beforehandThere are entry conditions and exit conditionsRelated commands: For, while, Until,selet,Use for commandRole:Assigns the element in the list to the

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

addition to Shebang, the # occupies the absolute beginning of the content, is the comment line, the interpreter ignores the contents of such a line;3. The explanation ignores all blank lines in the script;4. Lots of commands and keywords (if,else,then,do,while,for, ... ）Note: Once the shell script runs in the current shell according to Shebang's instructions, an interpreter (child

True when the length of a string is greater than 0 -Z str1 True when the length of a string is 0 Str True when the string is non-empty As an example, compare strings to test the user id:If ["$ (whoami)"! = ' root ']; Thenecho "You had no permission to run $ as Non-root user."Exit 1;Fi Numeric comparison (integer) operator Compare Results Num1-eq num2 Two numbers equal to True

Transfer from http://blog.chinaunix.net/uid-20328094-id-95121.htmlA very good bash scripting tutorial, at least not in contact with bash can read!Create a scriptThere are many different shells in Linux, but usually we use Bash (Bourne again

Write a second shell script today and write the after-class questions in "private cuisine". The problem needs to write a check whether a name exists, does not exist to create a file, there is a need to determine whether the name of the file, the file is deleted after the creation of a directory with the same name, if the directory is to delete this directory.First set up a basic condition: The Operation directory is/tmp/test/(note: If this directory d

Bash shell scripting Getting Started (ii)Use of the Read commandRole:Use read to assign the input value to one or more shell variables:-p Specifies the prompt to display-T TIMEOUTRead reads the values from the standard input, assigns a variable to each word, and all the remaining words are assigned to the last variable

From a programmer's point of view, the shell itself is a program written in C language, from the user's point of view, the shell is the user and the Linux operating system communication Bridge. Users can either enter command execution and use shell scripting to accomplish more complex operations. In the Linux GUI incre

is:Command Here, after the command that requires keyboard input, add the 101 Special methods of usage10.1 BracketsIn BASH, a pair of parentheses is generally used to find the value of an expression in parentheses, or the result of a command's execution, such as: (A=hello; echo $a), which acts as ' ... '.10.2 Colon: There are two meanings, one is to represent an empty statement, a bit similar to a single ";" in C, which means that the line is an empty

, The interpreter (interpreter) needs to read the source code that we wrote and convert it to the target (object), which is then run by the computer. Because each execution of the program is more than the compilation process, so efficiency has decreased.The advantage of using scripting languages is that they are mostly run at a higher level than the compiled language and can easily handle objects such as files and directories, and the disadvantage is

script rotatefile can solve this problem. This script can rename the message to save the file (assuming outmail) is OUTMAIL.1, and for outmail.1 it becomes outmail.2 and so on ... The code is as follows: #!/bin/sh # vim: set sw=4 ts=4 et: ver="0.1" help() {   cat How does this script work? After detecting a file name provided by the user, we perform a 9 to 1 loop. File 9 is named 10, file 8 is renamed to 9, and so on. After the loop is complete, we name the original file 1

# input Check:If [-Z ']; ThenError "Error:you must specify a file, use-h for help"FiFilen= "$"# Rename any. 1,. 2 etc File:For N in 9 8 7 6 5 4 3 2 1; DoIf [-F ' $filen. $n "]; Thenp= ' expr $n + 1 'echo "MV $filen. $n $filen. $p"MV $filen. $n $filen. $pFiDone# Rename the original file:If [-F "$filen"]; Thenecho "MV $filen $filen. 1"MV $filen $filen. 1Fiecho Touch $filenTouch $filenHow does this script work? After detecting a file name provided by the user, we perform a 9 to 1 loop. File 9 is na

Shell Getting Started Tutorial (1)-shell-JUSTKK's Column-Blog channel-csdn.nethttp://blog.csdn.net/justkk/article/details/43795131 Shell Getting Started Tutorial (2)-Variables and Parameters-JUSTKK-Blog channel-csdn.nethttp://blog.csdn.net/justkk/article/details/44081993

How to use PHP as a Shell scripting language. We all know that PHP is a very good dynamic web page development language (fast speed, short development cycle ......). However, only a few people realize that PHP can also be well written as S. We all know that PHP is a very good dynamic web page development language (fast speed, short development cycle ......). However, only a few people realize that PHP can a

Use PHP as the Shell scripting language. We all know that PHP is a very good dynamic web page development language (fast speed, short development cycle ......). However, only a few people realize that PHP can also be well written. we all know that PHP is a very good dynamic web page development language (fast speed, short development cycle ......). However, only a few people realize that PHP can also be a g

As we all know, PHP is a very good dynamic web development language (fast, short development cycle ...). ）。 But only a very small number of people realize that PHP can also be very good as the language of writing shell scripts, when PHP as the language of writing shell scripts, he is not as powerful as Perl or bash, but he has a good advantage, Especially for tho

As we all know, PHP (as the current mainstream development language) is a very good dynamic web development language (fast, short development cycle ...). ）。 But only a very small number of people realize that PHP (as the current mainstream development language) can also be very good as the language of writing shell scripts, when PHP (as the current mainstream development language) as the language of writing shell