Shell

The shell can often be seen: >/dev/null 2>&1/dev/null represents an empty device filewhere does the > delegate redirect to, for example: echo "1111" >/home/a.txt1 means stdout standard output, the system default is 1, so ">/dev/null" is equivalent

[ -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] is true if file exists. [ -f file]

First, expect explanation Expect allows us to automatically log on to remote machines, and can implement automatic remote execution of commands. Of course, if you use key authentication without a password, you can also implement automatic

This is the 6.828 first section of a small job, is to implement a shell, most of the source code is given, but compile a lot of bugs and warning found, so need to read the source and then change their own.The focus of this assignment is to

Shell Special variablesVariable meaning$ $ Gets the script name of the currently executing shell script, including the path and script name if the script has a path$n Gets the nth parameter in the currently executing shell script. But when n=1..9,

First, the demand      original file a for 1.7g file, with 5 1700 Mangyo look. There are also 2 auxiliary files b and C, b c files are only 2 column. a1 and b1 same, A2 and C1 a1 B2, c2" a4 a5, the target file is named d.txtSecond,

7. If you judge some special usageIf [-Z $a] This indicates what happens when the value of variable A is emptyIf Grep-q ' 123 ' 1.txt; Then what happens if the 1.txt contains a ' 123 ' rowif [!-e file]; Then what happens when the file doesn't

-----------------------------------------------------------------------------------------Only the environment variables are placed in the configuration file to automatically take effect each time the power-on. SOURCE command: Let the configuration

if [-f/etc/syslog.conf]; #判断文件是否存在Thensystest= ' sed-n '/^auth.info/p '/etc/syslog.conf '; #匹配 the/etc/syslog.conf file has a auto.info string and returns a string, Systest variable is received.if [-n \ "\ $systest \"]; #判断字符串是否存在ThenSed-e ' s/^auth.

Talk about the function call, I believe that everyone will not be unfamiliar, but for the beginner shell of me, Shell function call Way is a bit let me not very accustomed to, I also go a lot of detours, because the transfer of parameters when a

1. Write the shell script, calculate 1-100 's and;650) this.width=650; "src=" http://s3.51cto.com/wyfs02/M02/71/B2/wKiom1XWy-eBa3uqAAENi2u4ldc587.jpg "title=" 1.jpg " alt= "Wkiom1xwy-eba3uqaaeni2u4ldc587.jpg"/>2. Write the shell script, ask for a

 1, creating table: Create ' t1 ', ' F1 ', ' F2 ', ' F3 '                   #-------T1 is the table name, F1,F2 , F3 is the column family name  2, view all tables: list 3, view the structure of the table: describe ' t1 '  4, add a column family:

CTRL r: Command line appears reverse-i-search, input character will match command in input historyCTRL P: Go ahead and look through historyCtrl N: Looking back over historyCtrl A: Command headerCtrl e: Command line endCtrl F: Jump forward one

The while loop is used to continuously execute a series of commands and to read data from the input file; the command is usually a test condition. The format is: while Command Do If True done The following is an example of a basic while

[Email protected] ~]# mkdir scripts; CD scripts[Email protected] scripts]# VI sh01.sh#!/bin/bash declaring shell names# program: Description of Procedure Content# This program shows the "Hello world!" in the Your screen.# History:# 2005/08/23 Vbird

VIEditoris the standard for all UNIX and Linux systemsEditorThat it's powerful not inferior to any of the latest textEditor, here is simply a brief introduction to its usage and a small number of instructions. Because of any version of UNIX and

1. ls commandThe LS command is the meaning of listing directory contents (list directory Contents). Running it is to list the contents of a folder, possibly a file or a folder.The "ls-l" command lists the contents of the folder in detail mode (long

There are some files and directories under the current directory, each of which has several. txt files in each directory.It is now required to create a new directory in the current directory all, and all of those directories will have a. txt fileare

In the author's series of development tutorials, there is a relatively basic and important section: Development debugging. In the article I recommend two dynamic domain name resolution tools to deploy the local development environment as a server,

Network address Translation (NAT) has a port translation called NAPT that is network addressWhat NAT is:Devices inside the network are assigned private IP addresses, but NAT-enabled routers retain one or moreAn Internet IP address that is valid