[ncolug] Re: Linux Home Automation
- From: Mike <mikeb@xxxxxxxxxxxxxx>
- To: ncolug@xxxxxxxxxxxxx
- Date: Sat, 15 Dec 2007 20:55:56 -0500
Mike wrote:
Replying to myself...
I walked away and figured out I gave out conflicting information. Use
mktemp, then you won't have fuss with the file names. They are handled
there.
The date info still applies IMNSHO if you are creating the files.
Commented on testing for the existence of files and/or redirecting
output. One can redirect STDOUT and STDERR in the crontab file. This
will prevent you getting mail if any output is generated. This isn't
the best thing to do unless the output is meaningless. I like to have
the script catch any output or redirect it, then if something goes awry
during a run of cron you will get a mail that will be useful.
Other tidbits more applicable to multi user systems. Quit using ~/bin
for other than test purposes. Ask Chuck for a dissertation on the
headaches this will cause you, and to why it is a very bad practice.
I'm not going there.
I'd also use /tmp or /var/tmp for the files, again not ~/something.
Using either should include a test to ensure that the directory exists
before trying to write files to it. Yes it is a bit more work, it goes
back to using ~ again.
A script this short I probably wouldn't do the following on Linux.
Other *nix systems I would. I do this because I want to know *exactly*
what tool I'm calling. On the Solaris boxen at MSC one could find up to
4 different versions of a given tool. It ain't pretty when you get the
wrong one due to a PATH issue. All that said, what I do is set
variables for each tool called and then reference the variable.
Something like this.
LS=/usr/local/bin/ls
RM=/bin/rm
${LS} -1 /somedir/* | ...
I also tend to get rather anal and use ${} when using variables.
Certainly not required, it helps me with readability and there is some
reasoning to the usage in my brain.
Mike
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