Programmer Group

1. Basic grammar [condition] (note that there should be spaces before and after the condition) Note: if the condition is not empty, it is true, [666] returns true and [] returns false. 2. Common judgment conditions (1) Comparison between two integers = string comparison -lt less than -le less than or equal -eq equals (equal) -gt greater than ...

1.shell Shell command line interpreter, Linux scripting language 1.1 variables Common system variables: $HOME $PWD $SHELL $USERStrict space rules There must be no spaces on either side of the equal signThere are spaces in the variable. You can wrap it with "" or ()There must be a space between expr operatorsThere should b ...

Compiling environment Host hardware environment: $ uname -a Linux PC 4.4.0-42-generic #62-Ubuntu SMP Fri Oct 7 23:11:45 UTC 2016 x86_64 x86_64 x86_64 GNU/Linux 12 Host software environment: $ cat /etc/issue Ubuntu 16.04.1 LTS 12 Tools to install: sudo apt-get install libncurses5-dev sudo apt-get ...

Shell distribution script principle In the cluster, we often have this requirement: copy files to the same directory of all nodes in a circular way, and use commands separately from one node to another to improve efficiency. Core idea Encapsulation on rsync rsync command analysis characteristic rsync remote synchronization tool rsync is mainly ...

  1, Condition selection and judgment (if, case) 1.1 if statement usage and examples When we need to judge in the script, we can use the if statement to implement it. The specific syntax is as follows:    Single branch if judgment conditions; then Branch code with true condition　　fi    Double branch if   ...

If kept has 10 VIPs, how to check the traffic of each VIP? Here you can use the sar command to view the network card traffic. The premise is that when you keep listening to the network card. Set the subinterface when setting up the network card. That is, your network card is bound to the sub interface. In this way, eth0:0 and eth0:1 can see t ...

Shell is a program for the interaction between users and the operating system. It is often used to perform some automated or repetitive and cumbersome tasks. Now all Linux systems basically bring this program. We only need to write shell scripts and execute them directly. There is no need to install additional software and configure the compi ...

Let's talk about data analysis: Data collection: responsible for data collection Data cleaning: responsible for data filtering Data analysis: data operation and sorting Data display: output results in chart or table mode shell script data processing 1) Data retrieval: grep tr cut 2) Data processing: uniq sort tee paste xargs In the previous s ...

catalogue sed editor sed common options sed common operations: Basic Usage sed script format Example:    Search for alternatives Change configuration file   AWK    Basic usage Get IP address   Common built-in variables in awk sed editor sed is a flow editor that edits the data flow based on pre pro ...

1, Functions 1.1 function A statement block is defined as a function approximately equal to an alias, a function is defined, and then a function is referenced Encapsulated reusable code with specific functions 1.2 basic format of function Method I: [function] Function name (){ Command sequence [return x] #Use return or ...