Logging inside a bash script file - linux

Question

I have a pretty large script ( functions contains around 4000 lines of code) . Here is a part of it :
#!/bin/bash
. ./functions > /dev/null 2>&1
some_function(){
while true
do
CHOICE=$(whiptail --menu "\n\n\n\n\n\n\n\n" --title "Tools" --nocancel $window 20 \
"1" "Option1" \
"2" "Option2" \
"3" "Option3" 3>&1 1>&2 2>&3)
case $CHOICE in
1)echo $1 $2 $3;;
2)echo $2 $1 $3;;
3)echo $3 $2 $1;;
esac
done
}
while true; do
arr=()
for ((n=1; n<=$node_num; n++))
do
node+=($n NODE$n)
done
OPTION=$(whiptail --menu "\n\n\n\nPlease choose:\n\n\n" --title "tools" $window 20 "${node[#]}" \
case $OPTION in
1) some_function 1 2 3 ;;
2) some_function 2 1 3 ;;
3) some_function 3 1 2 ;;
esac
done
I want to log the commands executed in the script.
What I have tried so far is :
#!/bin/bash -x --> this will log all the output , but will also "spam" the logs with unneeded information like variable values etc. However this seems to be the best way so far...
I have tried #!/bin/bash -i , enabling history with set -o history . The disadvantage of this is it will log everything . When I call the function file for example it will log every single line as if it was executed .
I have tried creating a log function :
logthis(){
## print the command to the logfile
echo "$(date) $#" >> $historyfile
## run the command and redirect it's error output
## to the logfile
eval "$#" 2>> $historyfile
}
This seems to work most of the time. But when I do, for example:
case $OPTION in
1) logthis "some_function 1 2 3" ;;
2) some_function 2 1 3 ;;
3) some_function 3 1 2 ;;
esac
it will not work as I will lose the arguments 1 2 3
Do you have any other ideas of doing an elegant logging system inside a bash script?

Answer 1

Get rid of the eval in your log function. Just write "$#" to execute the passed command.
logthis() {
echo "$(date): $#" >> "$historyfile"
"$#" 2>> "$historyfile"
}
Then you can log a command by simply prepending logthis. No need for extra quotes.
logthis some_function 1 2 3
This will very nicely preserve all the arguments--even if they have whitespace or other special characters.
I'd recommend a minor improvement to the echo command as well. If you use printf %q it'll log arguments with whitespace better.
echo "$(date):$(printf ' %q' "$#")" >> "$historyfile"

Answer 2

Try set -v
That doesn't parse the commands like set -x, just outputs what gets executed.
set -v
: all the things 'in' $0, 'yay!'
outputs exactly : all the things 'in' $0, 'yay!'
Doesn't even parse $0.
Arguments recorded, minimal spam. ;)
Consider wrapping curlies around the main block of code to manage output logging.
{ # after setup to parse args, set vars & traps, declare funcs, etc
your bulk code here
} 2>&1 | tee /some/file.log
You can save the set -x spam for --verbose mode. ;)