set user id

I. file input/output functions 1. Basic I/O functions Open: Allow programs to access files Close: Terminate File Access Print: file write string Write: Write the formatting information to the file. Printf: format the string and output it to the

A summary of advanced programming v2cn in UNIX----Date, January 1, March 24, 2013Blog, http://blog.csdn.net/shunqiziranhao007/article/details/8712863----Netizens, master of Huashan, can take a look at reading notes if you are

Transferred from: http://zhpfbk.blog.51cto.com/4757027/1561926Includes common operating system features in Python's standard library OS moduleThe OS module introduces the following method: Import OSThe following are common usage methods for OS

The shell condition determines if the-Z to-D meaningShellfilestringless Terminal user[-A file] is true if file exists.[-B file] True if file exists and is a block special file.[-C file] True if file exists and is a word special.[-D file] True if

In addition to network communication, the server program must also take into account many other details of the problem, fragmented, but basically the template-style. ——— cited Linux server programs typically run in the background. Daemon is

As mentioned before, what is true and false in bash is judged by whether the end state of the command is zero. Return 0, that is true, return non 0, that is false.In bash, this is a formula that can affect a program's flow, called a conditional

From: http://m.jb51.net/article/56553.htm This article mainly introduced the shell script if condition judgment and the judgment condition summary, this article first gave the IF condition judgment the grammar, then gave the commonly used judgment

[-A file] is true if file exists.[-B file] True if file exists and is a block special file.[-C file] True if file exists and is a word special.[-D file] True if file exists and is a directory.[-E File] True if file exists.[-F file] True if file

by Francis_hao Oct 1,2017This article extracts the Man Handbook from bashConditional expressionsThe conditional expression is composed of a composite command [[or] built-in command test and [used for testing file properties and string or numeric

Linux User, user group Rights Management detailed Linux User Management Three important documents detailed: Linux login requires user name, password. The/etc/passwd file holds the user name. When you log in to Linux, Linux looks

Today, I met a sighup question, and then I went over it again:Some signals are handled by default to "Terminate +core", where the core indicates that when the process terminates, a core file is produced in the current working directory of the

[ -a FILE ] FILEtrue if it exists. [ -b FILE ] True if it FILE exists and is a block special file. [ -c FILE ] FILEtrue if a special file is present and is a word. [ -d FILE ] True if it

Binary comparison operators, comparing variables or comparing numbers.Note the difference between a number and a string.1. Integer comparison[CPP]View PlainCopyprint? -eq equals, such as:if [ "$a"-eq " $b"] -ne not equal to, such as:if [ "$a"

Dynamic libraries and static libraries are common in C + + development, where the dynamic library run-time load makes the executable program smaller, and updates the dynamic library without recompiling the executable program, as opposed to the

1, test-f file 2, [-F file] 3, [[-F file]][-F file1-a-F file2] logic with [-f file1-o-F file2] logic or [-f file1] && [-f file2] the same as a string operation best double quotes such as-n-z = = = And a space is added to both sides of the equals

1. String judgmentSTR1 = str2 When two strings have the same content, length is trueStr1! = str2 True when string str1 and str2 are not equal-N str1 True when the length of the string is greater than 0 (string non-null)-Z str1 True when the string

1.shell variablesLocal variables:A=1 (no spaces on both sides of the equal sign)Read-only variables:ReadOnly variable name = variable value (cannot be changed during use)Declaring variables:Linux assigns a value to a variable by default as a

Transferred from: http://www.cnblogs.com/kunhu/p/3699883.htmlMultiple user IDs and user group IDs are involved in the UNIX process, including the following:1. Actual user ID and actual user group ID: identify who I am. That is, the UID and GID of

For more secure storage of files, Linux gives different permissions to different files, each with the following three permissions : Owner permissions: What the file owner can do Group permissions: Actions that can be made by the user

This document records the rights management of Linux file system.First, the basic rights:1, the relationship between the user and the file:(1) file owner, owner, master, the first set of permissions for a file represents a master owned permission(2)