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UNIX / Linux Tutorial
1.14.3 Shell Initialization Scripts
1.15 So You Want To Strike Out On Your Own ?
1.14.3 Shell Initialization Scripts In addition to the shell scripts that you create, there are a number of scripts that the shell itself uses for certain purposes. The most important of these are initialization scripts, which are scripts executed by the shell when you log in. The initialization scripts themselves are simply shell scripts. However, they initialize your environment by executing commands automatically when you log in. If you always use the mail command to check your mail when you log in, you place the command in the initialization script so it will execute automatically. Both bash and tcsh distinguish between a login shell and other invocations of the shell. A login shell is a shell invoked when you log in. Usually, it's the only shell you'll use. However, if you "shell out" of another program like vi, you start another instance of the shell, which isn't your login shell. In addition, whenever you run a shell script, you automatically start another instance of the shell to execute the script. The initialization files used by bash are: /etc/profile (set up by the system administrator and executed by all bash users at login time), $HOME/.bash profile (executed by a login bash session), and $HOME/.bashrc (executed by all non-login instances of bash). If .bash profile is not present, .profile is used in-stead. tcsh uses the following initialization scripts: /etc/csh.login (executed by all tcsh users at login time), $HOME/.tcshrc (executed at login time and by all new instances of tcsh), and $HOME/.login (executed at login time, following .tcshrc). If .tcshrc is not present, .cshrc is used instead. A complete guide to shell programming would be beyond the scope of this book. See the manual pages for bash or tcsh to learn more about customizing the Linux /Unix environment. 1.15 So You Want To Strike Out On Your Own ? This chapter should give you enough information for basic Linux use. The manual pages are indispensable tools for learning about Linux. They may appear confusing at first, but if you dig beneath the surface, there is a wealth of information. We also suggest that you read a general Linux reference book. Linux has more features than first meet the eye. Unfortunately, many of them are beyond the scope of this book. Other recommended Linux books are listed in the Appendix.
1.1 Introduction 1.2.10 Referring To Home Directories 1.3.4 Copying Files
1.6 Exploring The File System 1.8 Wildcards 1.9.3 Pipes 1.10.3 Permissions Dependencies
1.12.4 Stopping And Restarting Jobs 1.13.3 Inserting Text 1.13.9 Including Other Files
1.14.3 Shell Initialization Scripts System Administration 2.3.1 The /etc/imitate file
2.4 Managing File Systems 2.6 Managing Users 2.6.5 Groups 2.7.2 gzip and compress
2.8.3 Making Backups To Tape Devices 2.9.1 Upgrading The Kernel
2.9.3 Installing A Device Driver Module
BOOK: LINUX QUICK COMMAND REFERENCE
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