Centos Basic Operations

1, CentOS7 to modify the host name

1) Hostname host name

Eg:

Hostname ityangs

Note: This way, only the temporary host name can be modified, when the machine is restarted, the host name changes back.

2) hostnamectl set-hostname xxx

Eg:

Hostnamectl Set-hostname ityangs

Note: You can modify the host name permanently by using this method. 2, Linux execution shell script in 4 ways to summarize

There are a number of ways to bash the shell script, now make a summary. Suppose we write a shell script with the file name hello.sh, the file location in the/data/shell directory, and already have execute permissions.

Method One: Switch to the directory where the shell script is located (at this point, called the Working directory) to execute the shell script:

Copy code code as follows:

Cd/data/shell

./hello.sh

/means to perform hello.sh in the current working directory. If you do not add./,bash may respond to an error message that finds no hello.sh. Because the current working directory (/data/shell) may not be listed in the default search path of the executing program, that is, it is not in the content of the environment variable pash. You can view the contents of the path with the Echo $PASH command. The current/data/shell is not in the environment variable pash, so it must be added./Before it can be executed.

Method Two: Execute the Bash shell script in an absolute way:

Copy code code as follows:

/data/shell/hello.sh

Method Three: Use bash or sh directly to execute a bash shell script:

Copy code code as follows:

Cd/data/shell

Bash hello.sh

Or

Copy code code as follows:

Cd/data/shell

SH hello.sh

Note that if you do this in method three, you do not have to set the shell's execution permissions beforehand, even without writing the first line in the shell file (specifying the bash path). Because method three is executed by passing the hello.sh as an argument to the SH (bash) command. This is not hello.sh yourself to execute, but is called by others to execute, so do not execute permissions. Then you don't have to specify a bash path.

Method Four: Execute bash shell scripts in the current shell environment:

Copy code code as follows:

Cd/data/shell

. hello.sh

Or

Copy code code as follows:

Cd/data/shell

Source hello.sh

The first three ways to execute a shell script are in the current shell (called the parent shell) to open a child shell environment, this shell script is executed in this child shell environment. After the shell script finishes, the child shell environment closes and then goes back to the parent shell. The method four is executed in the current shell.