Shell Programming and Scripting

I have a script that is inventorying (not sure if thats a word) my environment.

It goes out and pulls Hostname OS, IP, and ENV (dev, prod, etc)..then spits all that to a logfile

At the top of my script i have a check to see if the logfile exist.

Code:

[[ -f $LOGFILE ]] || touch $LOGFILE && echo "ENV" "\t" "HOSTNAME" "\t" "OS" "\t" "IPADDRESS"

What i want it to do is IF exist, do nothing...otherwise touch and echo header to file.

Currently every run it echos the header row.

I think you want something more like:

Code:

if [ ! -f $LOGFILE ]
then printf "ENV\tHOSTNAME\tOS\tIPADDRESS\n" > $LOGFILE
fi

You have to redirect the output into the file you want it in instead of just writing it to stdout while it is directed to your terminal. But if you redirect it with the command form you're using you'll end up with an empty file because the shell redirection will create the file before the initial test checks for its existence.

Note that I used printf rather than echo because there are many different versions of echo. According to the standards the results are undefined if any of the arguments to echo contain a backslash character. Historically System V echo accepted \ escapes and BSD echo did not. System V echo didn't accept any options (and if it got initial arguments starting with - it printed them as part of the output) while BSD echo used a -n option to omit the terminating newline usually added to the output (System V echo used \c at the end to terminate output without a terminating newline). The printf utility should work the same on any UNIX-like system.

Try the "-s" file test:
-s file file is not empty.

Code:

if [[ ! -s $LOGFILE ]] then
 touch $LOGFILE && echo "ENV" "\t" "HOSTNAME" "\t" "OS" "\t" "IPADDRESS"
fi

This still won't work. The output of the echo isn't redirected away from your terminal.