15.1 Initialization Files 
15.1.3 User specific initialization files
After the system-wide initialization file is read that sets system-wide defaults, the user initialization files for the appropriate shell are read. The user initialization files provide great flexibility to the user for customizing their environment. Login initialization and customization can be accomplished using the system-wide file /etc/profile by itself or in combination with the user-specific initialization files. Depending on the network administration policies, many custom settings could be placed in the /etc/profile file. This would set them automatically for all users, and they would not need user-specific initialization files. Since users do not have permission to modify the /etc/profile file, this would also prevent the users from modifying the login initialization settings. The user initialization files can be set up as templates by the system administrator, and then modified by the user. The user-specific initialization file(s) are stored in the home directory of the user. Depending on network administration policy, user-specific initialization files can perform all or part of the following:
  • Set Default Prompt - As described in Chapter 14
  • Define Default Printer - Provides access to local printer
  • Set Default Permissions - Set umask for new files and directories
  • Set Default Terminal Type - Used by vi and other tools
  • Set New Mail Location - Tells the shell where to look for new mail
  • Set noclobber - Prevent overwriting of files during redirection
  • Set Command Path - Defines directories to look in for executable files
  • Define Custom Commands - Defines user command aliases as described in Chapter 14