On Thu, Jan 20, 2000 at 12:23:09PM -0700, SoloCDM wrote:
| 1) Is it possible to effectively determine if a command executed
| successfully or failed?
Sure. Every command has an exit status, which is zero on success and
nonzero on failure (some commands have a well documented assortment of
nonzero exits for different types of failure in the manual entry,
though most simply exit with a 1 for all failures).
The shell stores in in the variable $? when the command completes:
some command
echo "exit status was $?"
However, it's cleaner to note that the shell considers commands to be its
expression components, thus:
if some command
then echo "The command worked."
else echo "The command failed."
fi
some command || echo "The command failed."
some command && echo "The command succeeded."
The "test" (aka "[") command is constructed around this principle, so
the common:
if [ some test expression ]
then
blah
fi
is just a special case - that [ ... ] isn't some special shellism,
you're just running the command "[".
| 2) If so, does it work on every command?
It's supposed to. If it doesn't, file a bug report with the author.
BTW, the "make" command depends very heavily on this behaviour, as the
make is meant to stop if some subcommand fails.
--
Cameron Simpson, DoD#743 [EMAIL PROTECTED] http://www.zip.com.au/~cs/
Courage is not the absence of fear, but rather the judgment that something
else is more important than fear. - Ambrose Redmoon
--
To unsubscribe: mail [EMAIL PROTECTED] with "unsubscribe"
as the Subject.
