Shell

1. Basic Concepts A, I/O redirection is usually related to FD, Shell FD is usually 10, namely 0~9; b, commonly used FD has 3, for 0 (stdin, standard input), 1 (stdout, standard output), 2 (stderr, standard error Output), the default and keyboard,

This is a simple shell instance. Here is a description of its requirements: Experiment five UNIX Shell program design Experiment content: Use UNIX shell programming language, write Unix shell application. Experiment requirements: The following

one, parentheses, bracket () 1. Single bracket ()① Command Group. The commands in parentheses will be executed in a new sub shell sequence, so the variables in parentheses cannot be used by the rest of the script.     Multiple commands in

Today, there is a problem with automating Jenkins deployments. I will kill other processes while executing the shell script, and this process is no longer executing, looking for resources and finding an article. This is because Jenkins by default

Environment variable Path: [Root@localhost ~]# set//check to see local and global Variables 2 kinds [Root@localhost ~]# env//View the system's Global environment variables [Root@localhost ~]# echo $PATH//View system environment variable path

The method of random number provided by C Srand and Rand, the former is to give the latter set of random number seed seeds. int rnd_num = 0; Srand (seed); Time (NULL) usually used to make seeds Rnd_num = rand (); Generate random numbers Methods

File descriptor abbreviation Description0 STDIN Standard Input1 STDOUT Standard output2 STDERR standard Error1. STDINcan come from the keyboard and can be entered from a redirected file.1 Cat 2 a #从键盘输入 3a #输出 4b #从键盘输入 5b #输出 6

Kinds:? Set: Used to display local variables, display variables for the current shell, including variables for the current user? ENV: Used to display environment variables and display variables for the current user.? Export: Used to display and set

Using Nmap to scan the surviving hosts in batches Knowledge Reserve: Grep,nmap First, install Nmap1. Install the compilation environment[[email protected] nmap-7.01]# yum install gcc g++ gcc-c++ -y2. Download Nmap using

Requirements: Use the free command to accurately monitor RAM utilizationKnowledge: GREP,FREE,AWK,BCThe script is as follows[[email protected] scripts]# cat mem.sh #!/bin/bash-# free-m represents output in m units, and if the memory is large enough,

"Conditional judgment"1. Judging by file type-B file to determine if the file exists and is a block device file (is a block device file is true)-c file to determine if the file exists and is a character device file (the character device file is true)

What is the exact difference between a ' terminal ', a ' shell ', a ' tty ' and a ' console '?A terminal is at the end of A electric wireA shell is the home of a turtleThe TTY is a strange abbreviationA console is a kind of cabinet.Well,

Shell Advanced StepConditional Select if statement to achieve conditional judgmentIf syntax: if Commands;then commands (if the command is true, the subsequent command will be executed, fi ends;)Elif Commands;then Commands (if the previous if is not

First, special symbols*: any of any characters1*1bak.zip 1. Tar 1. zip.bz21:1. TXT 21*2？ : An arbitrary character2? Tar 2. Tar#: Notes[[Email protected] ~\: de-intention[Email protected] ~]# a=3~]# echo $a3~"\ $a "$a|: Pipe SymbolThe function of

##################################################################################################Shell script:Scripts: Files that can be executed, implemented after running a certain function (command stacking, interactive)Standardize the general

Small Q: A person's career success, only%15 is due to his professional skills, the other%85 to rely on his interpersonalRelationship. The technique of the world, soft and hard relative, professional technology is a strong skill, and based on the

Original address: http://blog.sina.com.cn/s/blog_62eb16bb01014dbh.htmlOnce the trap captures the signal, there are three ways to react:(1) Execute a procedure to process this signal(2) The default action to accept the signal(3) Ignoring this

The Shell also supports functions. The Shell function must be defined before use.The Shell functions are defined in the following format:Function_name () { List of commands [return value]}If you prefer, you can also add keyword functions to

$ CD ' DirName $ ' and some special usages of pwd%/* shell variables in the command line state simply execute $ CD ' DirName $ ' is meaningless. Because he returns the "." of the current path.This command, written in a script file, returns the

Fly2015Here the shelling procedure is my love crack training of the job 2, compared to the job 1 A little stronger, but as long as the control of the shelling of the ESP Law, take off this Nspack Shell is not difficult, but it is quite interesting.