Help with implementing logging

Shell Programming and Scripting
1

I'm trying to add logging to an existing script which echos a number of lines to the screen. I've added a switch to the script that is going to suppress much of this output and put it in a file instead.

The way I envisioned it was like this:

$log would be set to either "" or the log files redirection

log=">> ./tstlogfile.txt"

echo "Text to terminal"

echo "text to log file" $log

I thought this would work, but it takes my redirection string literally... is there an easy way of doing this that I'm missing?

2

try

LOGFILE=`./tstlogfile.txt`
echo "text to terminal"
echo "text to logfile">> $LOGFILE
3

Yeah, I thought of that, but it would error when logging wasn't on because logfile would be empty.

4

Log file will not become empty, as this is not redirection (>), that is append operation (>>).

5

This (slightly edited) code works on our HP-UX machine.

LOGFILE=$LOGDIR/tstlogfile.txt
echo "text to terminal"
echo "text to logfile" >> $LOGFILE
6

I meant the variable $LOGFILE would be empty which would error when the line gets interpreted as:

echo "text to logfile" >>

You'd get an error:

syntax error: `newline or ;' unexpected
7

If your script doesn't use terminal for other purposes than logging, you can use exec
See tuto here Using exec
See example 19.2

8

Ah, yes. This looks like it will do the trick... thanks.

9

if you have tee command then you can do it like..

LOGFILE='./tstlogfile.txt'
echo "text to both terminal and log file" | tee -a $LOGFILE