bash scripting basics

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

Advanced Bash-scripting Guide (19th): maximum common divisor of two integers, bashscripting The example selected in this article is from the book "Advanced Bash-scripting Gudie", translated by Yang chunmin Huang Yi 1 #! /Bin/bash 2 # calculate the maximum common divisor of t

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 shell) is opened explaining the execution of the code, and the contents of the shell script are implemented in a ch

; Thenuserdel-r $USER [$DEBUG-eq 1] ECho "Delete $USER finished." else[$DEBUG-eq 1] echo "$USER not exist." Fidonefi Exercise: Write a script showlogged.sh, which uses the format: Showlogged.sh-v-c-h|--help where the-h option can only be used alone to display help information; the-C option displays the number of users logged on on the current system If you use the-V option at the same time, both the number of simultaneous users logged in and the information about the logged-on user are display

Advanced Bash-scripting Guide (17): use more to view gzip files, The example selected in this article is from the book "Advanced Bash-scripting Gudie", translated by Yang chunmin Huang Yi 1 #! /Bin/bash 2 # use more to view the gzip file 3 4 NOARGS = 65 5 NOTFOUND = 66 6 NOT

Advanced Bash-scripting Guide (15th): Test broken link files (broken link ), The example selected in this article is from the book "Advanced Bash-scripting Gudie", translated by Yang chunmin Huang Yi 1 #/bin/bash 2 # use a pure shell script to find the bad link file 3 # What

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 "variable name" in turn; The loop body is ex

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

Learn more about the character test of Linux and the practice of bash scriptingOne, character test options= =: Tests whether two strings are equal, equals true, and not equal to false.！ =: Tests whether two strings are unequal, unequal to true, and equal to false.-N String: Tests whether the specified string is empty, NULL is true, and is not NULL for false.-Z String: Tests whether the specified string is not empty, is not empty, is true, and Null is

/wyfs02/m02/7f/11/wkiom1cr12dwqsklaadjvt32yyi610.jpg " title=" help.jpg " alt=" Wkiom1cr12dwqsklaadjvt32yyi610.jpg " >. admuseradv abcdefg & nbsp options or incorrect parameter errors result in error messages 650) this.width=650; "src=" Http://s5.51cto.com/wyfs02/M02/7F/11/wKiom1cR16iQ3Av7AACRq6FruD0836.jpg "title=" Error.jpg "alt=" Wkiom1cr16iq3av7aacrq6frud0836.jpg "/>This article is from the "Xavier Willow" blog, please be sure to keep this source http://willow.blog.51cto.com/6574604/176440

Advanced Bash-scripting Guide (18): [[] and [] some special cases, bashscripting The example selected in this article is from the book "Advanced Bash-scripting Gudie", translated by Yang chunmin Huang Yi For example, [1-eq 1] [-n "'echo true 1> 2'"] # true. 1> 2 indicates to output the standard output to file descr