At 04:34 PM 10/10/02 -0400, Paul Kraus wrote:
>[...]
>A couple of easy questions I can't seem to find answers to.
Assuming we are talking about standard shell scripts (in practice, ones
that run using bash) ...
>1. How can I pass in parameters from the command line to use as
>variables.
> myscript value1 value2
These command-line arguments are accessed as $1 and $2 (and so forth).
>2. How can I have it dump a message to a log file if something fails and
>then cease running the script.
> if mount fail append to end of log1.txt "mounting failed",
>terminate script.
>
>I was under the impression that you could have a script terminate if a
>command failed by having && separate the commands but this just
>generates an error.
If it generates an error, you have the details wrong, because this is the
correct (or at least the common) way to to do it. It is basically a
programmers's trick ... it works because && is the logical AND operator,
and, in bash (and most Unix/Linux interpreters), it is evaluated left to
right. So ... first it evaluates whatever is on the left side of &&. If
that part is TRUE, then it evaluates the right side, but if it is FALSE it
does not evaluate the right side (since it knows without doing so that the
combined boolean expression evaluates to FALSE).
If the two parts are commands, then it executes the one on the left. If
execution returns a TRUE value (basically, this means that it does not
return an error), it executes the rifht-hand command, which might be
echo "something or other"
or
exit 0
If you look in your init-script directory (I forget where RH keeps this),
you'll find a ton of examples of how to do this.
BTW, you can find all this stuff in the man page for bash. It is about the
most difficult man page I've ever tried to read, though (the information
needed about bash is just too long for the man-page mechanism to handle),
so you'd do better to find a tutorial (use the usual search strategies) or
a book ... or look at the many examples on your system.
--
-------------------------------------------"Never tell me the odds!"--------
Ray Olszewski -- Han Solo
Palo Alto, California, USA [EMAIL PROTECTED]
-------------------------------------------------------------------------------
-
To unsubscribe from this list: send the line "unsubscribe linux-newbie" in
the body of a message to [EMAIL PROTECTED]
More majordomo info at http://vger.kernel.org/majordomo-info.html
Please read the FAQ at http://www.linux-learn.org/faqs
