. If it doesn't exist or is null, print the error message. If no error message is given, print parameter null or not set. N... n its value; otherwise print varname: followed by message, and abort the current command or script. Omitting message produces the default message parameter null ... as argument and returns the filename only; it is meant to be used with the shell's command substitution mechanism (see below). basename is less efficient th... to be an easy portable way to explicitly generate message or redirect output to stderr. The best method I've come up with is to use the /proc/ filesy
rings,
#+ but not strings and sealing wax, not to mention cabbages and kings . . .
# Using if [ ...... cho "Usage: `basename $0` filename" >&2
# Error message to stderr.
exit $E_NOARGS
# Returns 65 a...
echo "File $filename not found!" >&2 # Error message to stderr.
exit $E_NOTFOUND
fi
if [ ${f
