UNIX for Advanced & Expert Users

$ cat tst.ksh
#!/bin/ksh
 

echo "Abc" > $LOG_FILE
echo "Ret - $?"

$ ./tst.ksh
Abc
Ret - 0

$ ./tst.ksh
./tst.ksh[6]: : cannot open
Ret - 1

$ ksh --version
  version         sh (AT&T Research) 1993-12-28 s+
$ ksh -s <<'__EOF__'
echo "Abc" > $LOG_FILE
echo "Ret - $?"
__EOF__

ksh[1]: : cannot open
Ret - 1

mute@thedoctor:~$ echo "Hello" > "${LOG_FILE:-/dev/null}"
mute@thedoctor:~$ echo $?
0