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1.1       root        1: .TI CSHELL/GENERAL
                      2: The C Shell Command Interpreter
                      3: 
                      4: 
                      5: The Unix shell is a program that accepts commands from a user
                      6: and calls up programs to perform them.
                      7: As it is also the only way of calling up programs,
                      8: the shell effectively surrounds the Unix kernel, which is a special
                      9: program having exclusive access to the computer hardware (memory,
                     10: processor, disks, etc.) which other programs need to run.
                     11: 
                     12: Most Unix systems in the world offer users the choice of logging in to
                     13: one of two shells:  (1) the standard shell from Bell Labs,
                     14: also called the Bourne shell after its author; or (2) the C shell
                     15: from UC Berkeley, reputed to have a syntax like the C language.
                     16: The C shell is more convenient for interactive use than the Bourne shell,
                     17: although it is less efficient for certain applications.
                     18: 
                     19: The C shell provides a variety of very useful services,
                     20: but not always in a particularly obvious way.
                     21: This is partly the fault of the shell and partly the fault
                     22: of the documentation.
                     23: The ultimate reference consists of the tersely worded
                     24: manual pages for "csh" (type "man csh" to see them).
                     25: As most people find this difficult to read, a document called "An
                     26: Introduction to the C Shell" is also available.
                     27: Here is a brief list of the C shell's features.
                     28: 
                     29: History Substitution:
                     30: allows previous commands to be redone, possibly with changes
                     31: 
                     32: Job Control:
                     33: allows programs to be switched from the foreground to the background,
                     34: putting programs on hold while intermediate results are checked
                     35: 
                     36: Command Aliases:
                     37: provides for renaming commands, abbreviating long commands, or
                     38: turning off selected commands
                     39: 
                     40: C Shell Programming:
                     41: has many useful high-level control structures and variable handling
                     42: capabilities which make conventional programming less attractive
                     43: 
                     44: Filename Substitutions:
                     45: provides for abbreviating groups of files and selecting filenames
                     46: based on patterns
                     47: 
                     48: Input/Output Redirection:
                     49: has input/output constructs for diverting input from any file or program
                     50: and output to any file or program
                     51: 
                     52: Start Up Processing at Login:
                     53: provides for commands to be executed automatically on logging in
                     54: and customization of personal accounts
                     55: 
                     56: The help topics on the C shell below do not cover the entire
                     57: story and some of them will be revised in the near future.
                     58: You might do well to read them in the order of the list,
                     59: though this is not required.
                     60: 
                     61: general          The C Shell Command Interpreter
                     62: internals        Internal Operation of the C Shell
                     63: flowcontrol      Control Statements:  Branching and Looping
                     64: expressions      Expressions:  Arithmetic, Logic Operations, and Decisions
                     65: history          Reusing Previous Commands and Command Parts
                     66: aliases          Renaming and Abbreviating Commands

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