Customizing a User's Work Environment
Part of setting up a user's home directory is providing user initialization files for the user's login shell. A user initialization file is a shell script that sets up a work environment for a user after the user logs in to a system. Basically, you can perform any task in a user initialization file that you can do in a shell script. However, a user initialization file's primary job is to define the characteristics of a user's work environment, such as a user's search path, environment variables, and windowing environment. Each login shell has its own user initialization file or files, which are listed in the following table.
Table 4-14 User Initialization Files for Bourne, C, and Korn Shells
Table 4-15 Default User Initialization Files
You can use these files as a starting point and modify them to create a standard set of files that provide the work environment common to all users. Or, you can modify these files to provide the working environment for different types of users. Although you cannot create customized user initialization files with the Users tool, you can populate a user's home directory with user initialization files located in a specified “skeleton” directory. You can do this by creating a user template with the User Templates tool and specifying a skeleton directory from which to copy user initialization files.
For step-by-step instructions on how to create sets of user initialization files for different types of users, see How to Customize User Initialization Files.
When you use the Users tool to create a new user account and select the create home directory option, the following files are created, depending on which login shell is selected.
Table 4-16 Files Created by Users Tool When Adding a User
If you use the useradd command to add a new user account and specify the /etc/skel directory by using the -k and -m options, all three /etc/skel/local* files and the /etc/skel/.profile file are copied into the user's home directory. At this point, you need to rename them to whatever is appropriate for the user's login shell.
Using Site Initialization Files
The user initialization files can be customized by both the administrator and the user. This important feature can be accomplished with centrally located and globally distributed user initialization files, called site initialization files. Site initialization files enable you to continually introduce new functionality to the user's work environment, while enabling the user to customize the user's initialization file.
When you reference a site initialization file in a user initialization file, all updates to the site initialization file are automatically reflected when the user logs in to the system or when a user starts a new shell. Site initialization files are designed for you to distribute site-wide changes to users' work environments that you did not anticipate when you added the users.
You can customize a site initialization file the same way that you customize a user initialization file. These files typically reside on a server, or set of servers, and appear as the first statement in a user initialization file. Also, each site initialization file must be the same type of shell script as the user initialization file that references it.
To reference a site initialization file in a Bourne-shell or Korn-shell user initialization file, place a line similar to the following at the beginning of the user initialization file:
Avoiding Local System References
You should not add specific references to the local system in the user initialization file. You want the instructions in a user initialization file to be valid regardless of which system the user logs into.
Table 4-17 Basic Features of Bourne, C, and Korn Shells
A shell maintains an environment that includes a set of variables defined by the login program, the system initialization file, and the user initialization files. In addition, some variables are defined by default.
A shell can have two types of variables:
In the C shell, you use the lowercase names with the set command to set shell variables. You use uppercase names with the setenv command to set environment variables. If you set a shell variable, the shell sets the corresponding environment variable. Likewise, if you set an environment variable, the corresponding shell variable is also updated. For example, if you update the path shell variable with a new path, the shell also updates the PATH environment variable with the new path.
In the Bourne and Korn shells, you can use the uppercase variable name equal to some value to set both shell and environment variables. You also have to use the export command to activate the variables for any subsequently executed commands.
For all shells, you generally refer to shell and environment variables by their uppercase names.
In a user initialization file, you can customize a user's shell environment by changing the values of the predefined variables or by specifying additional variables. The following table shows how to set environment variables in a user initialization file.
Table 4-18 Setting Environment Variables in a User Initialization File
The following table describes environment variables and shell variables that you might want to customize in a user initialization file. For more information about variables that are used by the different shells, see the sh(1), ksh(1), or csh(1) man pages.
Table 4-19 Shell and Environment Variable Descriptions
The PATH Variable
When the user executes a command by using the full path, the shell uses that path to find the command. However, when users specify only a command name, the shell searches the directories for the command in the order specified by the PATH variable. If the command is found in one of the directories, the shell executes the command.
A default path is set by the system. However, most users modify it to add other command directories. Many user problems related to setting up the environment and accessing the correct version of a command or a tool can be traced to incorrectly defined paths.
Setting Path Guidelines
Here are some guidelines for setting up efficient PATH variables:
Setting a User's Default Path
This is an example of how to set a user's default path.
The following examples show how to set a user's default path to include the home directory and other NFS mounted directories. The current working directory is specified first in the path. In a C-shell user initialization file, you would add the following:
set path=(. /usr/bin $HOME/bin /net/glrr/files1/bin)
In a Bourne-shell or Korn-shell user initialization file, you would add the following:
PATH=.:/usr/bin:/$HOME/bin:/net/glrr/files1/bin export PATH
The LANG and LC environment variables specify the locale-specific conversions and conventions for the shell. These conversions and conventions include time zones, collation orders, and formats of dates, time, currency, and numbers. In addition, you can use the stty command in a user initialization file to indicate whether the terminal session will support multibyte characters.
The LANG variable sets all possible conversions and conventions for the given locale. You can set various aspects of localization separately through these LC variables: LC_COLLATE, LC_CTYPE, LC_MESSAGES, LC_NUMERIC, LC_MONETARY, and LC_TIME.
The following table describes some of the values for the LANG and LC environment variables.
Table 4-20 Values for LANG and LC Variables
For more information on supported locales, see the International Language Environments Guide.
Example 4-1 Setting the Locale Using the LANG Variables
setenv LANG de_DE.ISO8859-1
In a Bourne-shell or Korn-shell user initialization file, you would add the following:
LANG=de_DE.ISO8859-1; export LANG
Default File Permissions (umask)
When you create a file or directory, the default file permissions assigned to the file or directory are controlled by the user mask. The user mask is set by the umask command in a user initialization file. You can display the current value of the user mask by typing umask and pressing Return.
The user mask contains the following octal values:
Note that if the first digit is zero, it is not displayed. For example, if the user mask is set to 022, 22 is displayed.
To determine the umask value you want to set, subtract the value of the permissions you want from 666 (for a file) or 777 (for a directory). The remainder is the value to use with the umask command. For example, suppose you want to change the default mode for files to 644 (rw-r--r--). The difference between 666 and 644 is 022, which is the value you would use as an argument to the umask command.
You can also determine the umask value you want to set by using the following table. This table shows the file and directory permissions that are created for each of the octal values of umask.
Table 4-21 Permissions for umask Values
The following line in a user initialization file sets the default file permissions to rw-rw-rw-.
User and Site Initialization Files Examples
The following sections provide examples of user and site initialization files that you can use to start customizing your own initialization files. These examples use system names and paths that you need to change for your particular site.
Example 4-2 The .profile File
(Line 1) PATH=$PATH:$HOME/bin:/usr/local/bin:/usr/ccs/bin:. (Line 2) MAIL=/var/mail/$LOGNAME (Line 3) NNTPSERVER=server1 (Line 4) MANPATH=/usr/share/man:/usr/local/man (Line 5) PRINTER=printer1 (Line 6) umask 022 (Line 7) export PATH MAIL NNTPSERVER MANPATH PRINTER
Example 4-3 The .cshrc File
(Line 1) set path=($PATH $HOME/bin /usr/local/bin /usr/ccs/bin) (Line 2) setenv MAIL /var/mail/$LOGNAME (Line 3) setenv NNTPSERVER server1 (Line 4) setenv PRINTER printer1 (Line 5) alias h history (Line 6) umask 022 (Line 7) source /net/server2/site-init-files/site.login
Example 4-4 Site Initialization File
The following shows an example site initialization file in which a user can choose a particular version of an application.
# @(#)site.login main: echo "Application Environment Selection" echo "" echo "1. Application, Version 1" echo "2. Application, Version 2" echo "" echo -n "Type 1 or 2 and press Return to set your application environment: " set choice = $< if ( $choice !~ [1-2] ) then goto main endif switch ($choice) case "1": setenv APPHOME /opt/app-v.1 breaksw case "2": setenv APPHOME /opt/app-v.2 endsw
This site initialization file could be referenced in a user's .cshrc file (C shell users only) with the following line:
In this line, the site initialization file is named site.login and is located on a server named server2. This line also assumes that the automounter is running on the user's system.