Intel XENIX 286 Programmers Guide (86) - Tenox.tc

csh: C Shell XENIX Programming
The C shell variable time is set to 15, causing the C shell to automatically print
statistics lines for commands that execute for at least 15 seconds of CPU time. The
variable history is set to 10, indicating that the C shell will remember the last 10
commands typed in its history list (described later). Finally, the XENIX mail program is
invoked.
When the C shell finishes processing the .login file, it begins reading commands from the
terminal, prompting for each with
%
When you log out (by giving the logout command) the C shell prints
logout
and executes commands from the file .logout if it exists in your home directory. After
that, the C shell term inates and XENIX logs you off the system.
Using Shell Variab les
The C shell maintains a set of variables. For example, in the above discussion, the
variables history and time had the values 10 and 15. Each C shell variable has as its
value an array of zero or more strings. C shell variables may be assigned values by the
set command, which has several forms, the most useful of which is
set name = value
C shell variables can be used to store values to be used later in commands through a
substitution mechanism. The C shell variables most commonly referenced are, however,
those that the C shell itself refers to. By changing the values of these variables you can
directly affect the behavior of the C shell.
One of the most important variables is path, which contains a list of directory names.
When you type a command name at your terminal, the C shell examines each named
directory in turn until it finds an executable file with a name that corresponds to the
name you typed. The set command with no arguments displays the values of all
variables currently defined in the C shell. The following example shows typical default
values:
argv ()
home /usr/bill
path (. /bin /usr/bin)
prompt %
shell /bi n/csh
status 0
This output indicates that the variable path begins with the current directory indicated
by dot (.), then /bin, and last /usr/bin. Your own local commands may be in the current
directory. Normal XENIX commands reside in /bin and /usr/bin.
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