Difference between revisions of "Centos Bash Shell Scripts"
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The BASH runtime configuration files (/etc/bashrc and ~/.bashrc) are typically used to set aliases and variables that must be present in the BASH shell. They are executed immediately after a new login as well as when a new BASH shell is created after login. The /etc/bashrc file contains aliases and variables for all users on the system, whereas the ~/.bashrc file contains aliases and variables for a specific user. <br /> | The BASH runtime configuration files (/etc/bashrc and ~/.bashrc) are typically used to set aliases and variables that must be present in the BASH shell. They are executed immediately after a new login as well as when a new BASH shell is created after login. The /etc/bashrc file contains aliases and variables for all users on the system, whereas the ~/.bashrc file contains aliases and variables for a specific user. <br /> | ||
The other environment files are only executed after a new login. The /etc/profile file is exe- cuted after login for all users on the system and sets most environment variables, such as HOME and PATH. After /etc/profile finishes executing, the home directory of the user is searched for the hidden environment files. bash_profile, .bash_login, and .profile. If these files exist, the first one found is executed; as a result, only one of these files is typically used. These hidden environment files allow a user to set customized variables independent of BASH shells used by other users on the system; any values assigned to variables in these files override those set in /etc/profile, /etc/bashrc, and ~/.bashrc due to the order of execution | The other environment files are only executed after a new login. The /etc/profile file is exe- cuted after login for all users on the system and sets most environment variables, such as HOME and PATH. After /etc/profile finishes executing, the home directory of the user is searched for the hidden environment files. bash_profile, .bash_login, and .profile. If these files exist, the first one found is executed; as a result, only one of these files is typically used. These hidden environment files allow a user to set customized variables independent of BASH shells used by other users on the system; any values assigned to variables in these files override those set in /etc/profile, /etc/bashrc, and ~/.bashrc due to the order of execution | ||
==Structure of a bash Script== | |||
#!/bin/bash | |||
[[File:Escape sequence.jpg|thumb|Escape Sequence]] | |||
Revision as of 20:44, 7 March 2019
List Environment Variables
set # you can | to grep to filter or env
Environmental Files
Files that execute each time a user logs in to bash shell
/etc/profile /etc/bashrc ~/.bashrc ~/.bash_profile ~/.bash_login ~/.profile
The BASH runtime configuration files (/etc/bashrc and ~/.bashrc) are typically used to set aliases and variables that must be present in the BASH shell. They are executed immediately after a new login as well as when a new BASH shell is created after login. The /etc/bashrc file contains aliases and variables for all users on the system, whereas the ~/.bashrc file contains aliases and variables for a specific user.
The other environment files are only executed after a new login. The /etc/profile file is exe- cuted after login for all users on the system and sets most environment variables, such as HOME and PATH. After /etc/profile finishes executing, the home directory of the user is searched for the hidden environment files. bash_profile, .bash_login, and .profile. If these files exist, the first one found is executed; as a result, only one of these files is typically used. These hidden environment files allow a user to set customized variables independent of BASH shells used by other users on the system; any values assigned to variables in these files override those set in /etc/profile, /etc/bashrc, and ~/.bashrc due to the order of execution
Structure of a bash Script
#!/bin/bash
