what in shell

A signal is a mechanism for inter-process communication. It provides an asynchronous software interruption for an application to receive commands (that is, signals) sent by other active terminals ). After an application receives a signal, there are

In shell, what are the special definitions of numbers? -- Linux general technology-Linux programming and kernel information. The following is a detailed description. LOG_DIR =/var/log ROOT_UID = 0 # $ when the UID is 0, the user has the root user

Interaction with mysql in shell script 1: [Plain] mysqlCMD = "mysql-h $ {MYSQL_HOST}-P $ {MYSQL_PORT}-u $ {MYSQL_USER}-p $ {MYSQL_PASS}" create_table_ SQL = "CREATE TABLE IF NOT EXISTS $ {MYSQL_DB_NAME }. $ {access_table_name} (id INT (10) not null

Article Title: programming vim + ctags + taglist (ubuntu) in shell ). Linux is a technology channel of the IT lab in China. Includes basic categories such as desktop applications, Linux system management, kernel research, embedded systems, and open

In shell programming, the test command-General Linux technology-Linux programming and kernel information is provided. The following is a detailed description. I just got started with linux and learned the shell programming if command (I have never

The little-known secret in shell command line-Linux general technology-Linux technology and application information. The following is a detailed description. /* Pass the test in linux */ One day, you wrote a very long command. $ Echo

EXEC command in Shell 1.-exec parameter in find In the current directory (including subdirectories), find all TXT files and find the rows containing the string "bin" Find./-name "*. txt"-exec grep "bin "{}\; Delete all TXT files in the

To test and replace variables in shell, we often need to determine whether a variable exists at some time point. if a variable exists, use the existing settings. if the variable does not exist, give a common setting. (1) If the variable is not set

1. FTP automatically logs in to batch download files.##### From/home/data on the FTP server to the local/home/databackup #####! /Bin/bashFTP-n Open 192.168.1.171User guest 123456.BinaryCD/home/DataLCD/home/databackupPromptMget *CloseBye!2. FTP

1. Use grep (the result is enclosed in parentheses. I wonder if I can match the content in the brackets only) $ A = 'abc [EDG] adfirpqu '$ echo $ A | grep-O '\[. * \] '# escape [EDG] $ B = 'abc (EDG) adfirpqu' $ echo $ B | grep-O '(. *) '(EDG) 2.

Suppose we define a variable: file =/dir1/dir2/dir3/my.file.txt You can replace $ {} with different values: $ {file # */}: Delete the first/and its left string: dir1/dir2/dir3/my.file.txt $ {file # */}: Delete the last/and its left string:

The color code is basically clipped between "\ e [" and "m": \ e [32; 1 m  You can use \ e [0 m to disable color output. In particular, when B is set to 1, the highlighted and bold text is displayed. Common color codes:  Foreground background color -

In the past, when I was writing code, I encountered a problem with the file path. for example, extract the directory or file name of the file path and determine whether the directory or file exists. every time you encounter such a problem, you

If parameters in Shell in Linux[-A file] true if the file exists.[-B file] If the file exists and is a special block file, it is true.[-C file] If the file exists and is a special word file, it is true.[-D file] If the file exists and is a directory,

Here I want to talk about the parentheses, braces, and variables in several shells. The command usage is as follows: 1. $ {var}2. $ (CMD)3. () and {}4. $ {var:-string}, $ {var: + string}, $ {var: = string}, $ {var :? String}5. $ (exp ))6. $ (VAR %

Use of if in shell, shellif useCompare if in shellShell determines whether an array contains an element:Ary = (1 2 3)A = 2If [["$ {ary [@]}" = ~ "$ A"]; thenEcho "a in ary"ElseEcho "a not in ary"FiThe method to compare the two strings is as

Special variables in Shell   $0 File Name of the current script $ N N is a number starting from 1. $1 represents the first parameter, $2 represents the second parameter, and $ {10} represents the tenth parameter.

Conditions test statement and Shell condition test statement in Shell Shell has conditional test statements. Generally, the test or [] commands are used to complete the test. They are conditional judgment statements if ~ The basis of the then

Solution: show only-bash-4.1 in shell command line # Do not show users and pathsToday, I accidentally typed the home Directory deletion command. Although it was not deleted for various reasons, many files and directories in the home directory were

Password Change in non-interactive mode in Shell scriptsToday, when I wrote a shell script, I found that the user's password needs to be set and the password is set to interactive. This is obviously not good in the script, So I went online to search