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

XENIX Programming Programming Commands
csh (continued)
If a command is run detached (followed by &), then the default standard input for the
command is the empty file /dev/null. Otherwise, the command receives the
environment in which the shell was invoked as modified by the input-output parameters
and the presence of the command in a pipeline. Thus, unlike some previous shells,
commands run from a file of shell commands have no access to the text of the
commands by default; rather, they receive the original standard input of the shell. The
>
+ * I % - ( )
Here, the precedence increases from left to right, with the operators
== and !=
=, < , and >
>
+ and -
*, !, and %
forming groups at the same level. The == and != operators compare their arguments as
strings; all others operate on numbers. Strings that begin with 0 are considered octal
numbers. Null or missing arguments are considered 0. The results of all expressions are
strings, which represent decimal numbers. It is important to note that no two
components of an expression can appear in the same word. Except when adjacent to
components of expressions that are syntactically significant to the parser--& I < > ( ) -they
should be surrounded by spaces.
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