Now centos7 is using the bash software, you can view the bash version through the following command:
[[email protected] ~]# cat /etc/redhat-release #View the system version
CentOS Linux rele
Category: Unix
The UNIX operating system (Eunice) is a powerful multi-user, multi-tasking operating system that supports multiple processor architectures. According to the classification of the operating system, it is a time-sharing operating system. It was first developed by KenThompson, Dennis Ritchie and Douglas McIlroy in 1969 Developed in AT&T’s Bell Labs in the year. At present, its trademark rights are owned by the International Open Standards Organization, and only UNIX systems that conform to a single UNIX specification can use the name UNIX, otherwise it can only be called UNIX-like (UNIX-like)
What is “TTY” on Unix – FreeBSD?
“The uprintf() function outputs to the current process’ control tty”
This is the description of uprintf() from Freebsd MAN.
I Don’t understand what is a tty?
Thank you. Holiday!
Once u
Getopts in the shell
getopts is a built-in command of the shell.
getopts optstring name [args]
OPTIND,OPTARG,OPTERR
getopts is used by the shell program to analyze positional parameters. optstring contains
Shell script prints ninety-nine multipliers
The shell script prints the nine-nine-nine multiplication table #!/bin/bash
for i in {1..9}
do
for j in {1..9}
do
if [$j -le $i]
then
echo -n “${j}X${i}= $(($i*$j)) ”
fi
done
RPM and YUM
rpm is an open software package management system, the original full name is red hat package management
rpm -i package name install software -ivh display the installation process
rpm -e
MacOS – How to add the parameters of the OSX LaunchD PLIST to the pipe output to the log file?
I have tried many different changes, but I can’t make it work.
I have a plist file:
authority management
Linux users and user groups (authority management) user management useradd create users
-c — Specify user description -d—specify home directory, default home directory /home under the sam
Shell script for While Until loop
Flow controlLogic processing in programming: Sequential execution
Select execution
Circular execution Loop Loop execution
Repeat a certain code segment several times
How many times it repeats
T
Shell script Advanced (for, while, continue, break, select, etc.)
Advanced script oneOne, the second way of writing for loop:
As we all know, there are two ways of writing for
< strong>How to write directly:
Two parentheses must be written after
Execution method of shell scripts
When the Shell script runs, it will first look for the system environment variable ENV, which specifies the environment file (the order of loading is usually /etc/profile, ~/.bash_profile, ~/.bashr