How to append the rest of the command from a variable? - ksh

Question

In the sample bellow, I would like to print text on the screen and also append this text into file, when the variable cpstdout is set to 1. Otherwise only print the text on screen. I need to have the echo part flexible to the append variable. Is there any way to correct my code?
#!/bin/ksh
cpstdout=1
if [ $cpstdout -eq 1 ]; then
append="| tee somefile"
else
append=""
fi
echo "test string" $append
Now the result is just like this:
./test.sh
test string | tee somefile
-no file is created of course
example of print function:
print_output(){
printf "\t/-------------------------------------------------\\ \n"
for i in "$#"; do
printf "\t| %-14s %-32s |\n" "$(echo $i | awk -F, '{print $1}')" "$(echo $i | awk -F, '{print $2}')"
shift
done
printf "\t\-------------------------------------------------/\n"
}

Answer 1

Define your appending command as a function:
output_with_append() {
tee -a somefile <<<"$1"
}
Then, in the if, set a variable to the appropriate outputting function:
if [ $cpstdout -eq 1 ]; then
output=output_with_append
else
output=echo
fi
Finally, use variable expansion to run the command:
$output "test_string"
Note that I've used tee -a since you said you wanted to append to a file and not overwrite it.
Setting cpstdout to $1 so we can control it through a command-line parameter:
cpstdout="$1"
A example session then looks like this:
$ ./test.sh 1
test_string
$ ./test.sh 1
test_string
$ cat somefile
test_string
test_string
$ ./test.sh 0
test_string
$ cat somefile
test_string
test_string