unix and linux system administration handbook

pipelines are generally linear, but it is often helpful to insert a copy of the data stream from the middle into a file, or send it to a terminal window. This can be done with the tee command, which sends its standard input both to the standard output and to a file specified on the command line. You can think of it as a tee on a pipe.For example, the following command sends the output value of date to the standard output and redirects the output to the Date.txt file:Date tee ./Date:notoginseng:

Date Created: 2016/02/29Update on: 2016/02/29 Shell variables cannot be left blank on both sides of the equals sign, otherwise the shell will mistake the variable name for the command name Variables enclosed in double quotes can be replaced with * and? The file name matches the meta-character extension) and the variable extension, and the single quotation marks do not handle the variable. The left quotation mark ', which handles a mechanism similar to a double quote, is able to execu

You can use the machine (computer) unique code + upload IP + current timestamp + GUID (+ random number), and then MD5 as the file name. The machine's unique code has the CPU information of the computer and the MAC address, both of which need to be obtained under the Linux or Unix system.Get CPU information from your computerfunction Onlyu () {$a = ";$b = Array ();if (function_exists (' exec ')) {if (mailto:

1. The WHO command reads the contents of the system log to display the user who is currently logged in.2, Unix system to keep the data in the file, you can call the operation file through the following system:Open (filename, how) creat (filename, mode) read (FD, buffer, AMT) write (FD, buffer, AMT) Lseek (FD, distance, base) Close (FD)3, the process of the file r

relatively long-term.(5) A program can act as a running program for multiple processes, and a process can run multiple programs.(6) The process has the ability to create other processes, and the program does not. EXEC and Fock briefThe exec system calls the process to reinitialize from the specified program, although the process is still in progress, but the program has changed . The Fock system call creat

use GCC (1) because the LD (1) interface may change. 3. Shared Library is loaded when the program starts. When an application loads a shared library, other applications can still load the same shared library. Based on the usage of Linux, the shared library also has other flexible and exquisite features: Updating the library does not affect the use of the old, non-backward compatible version of the application; when executing a specific program, it

Use a PHP script to modify the password of a Linux or Unix system. Required Tools and installation: you must install the following tools and software: Shell script for password modification; Sudo access; ApacheorLighttpdweb server; PHP server program. Step 1: install the required tools and installation: You must install the following tools and software: -Shel

This article describes how to use a PHP script to modify a Linux or Unix system password. Required Tools and Installation: You must install the following tools and software: – The shell script that modifies the password; –sudo access rights; –apache or LIGHTTPD Web server; –php Service-side program. Step 1: Install shell scripts that can modify user passwords Thi

In the analysis of live555CodeOccasional acquisition: If (fisfirstpacket) {// record the fact that we're starting to play now: gettimeofday ( fnextsendtime, null );} UNIX and Linux time systems start from epoch, in seconds. Epoch is the Greenwich Mean Time (Greenwich Mean Time) specified at 00:00:00, January 1, January 1, 1970. At present, most Unix systems

From: http://hi.baidu.com/rocsky/item/9376ef4d002397ea1e19bcd8 I. Aix 1. view the number of CPUs: (1) Since aix5.3, smtctl introduces the SMT (simultaneousmulti-threading) function for power5 machines. It allows two processing threads to run on the same processor, for an operating system, a physical processor logically becomes two processing units (logical processor ). SMT function enabled: the number of logical CPUs is twice the number of physical C

This series of articles provides some personal notes on the Unix toolbox.System Running kernel and system information: # Uname-#Obtain the kernel version (and BSD Version) # Lsb_release-#Display any LSB release version information # Cat/etc/Suse-release # Get SuSEVersion # Cat/etc/debian_version # Get Debian version Use/etc/distr-release, where distr (release code) = LSB (UBUNTU), RedHat, Gentoo, Mandrake,

The following list contains the single-process resource parameter limits for Unix/Linux systems. The rlimit_core parameter is much used in server development (when core dump is required ). Code snippet: memset(limit, 0, sizeof(limit)); limit.rlim_cur = RLIM_INFINITY; limit.rlim_max = RLIM_INFINITY; if(setrlimit(RLIMIT_CORE, limit)) {spd_log(LOG_WARNING, " unable to disable core size res li

My operation, I download the book source code on the official website, after the Windows decompression FTP tool to the Linux virtual machineThen make finds an error such as:No rule to make target '. /libtlpi.a ', needed byDepressed for a long time!Scenario: The Source code compression package FTP to the virtual machine in the decompression, make is successful!Attention, habits: always unzip in LinuxLinux/unix