I have been trying to find online what these if statement mean. Below are a few.
if [ "${snums[k]}" != "NA" -a ! -f "${aliases[k]}.4dfp.img" ]; then
if [ -f "$dcmfile" -a -n "`cat $dcmfile`" ]; then
The -a
used in these two examples do not make senses to me.
-a
or-o
is that they have been declared "obsolescent" by POSIX. Script authors are strongly encouraged to use the shell's&&
and||
instead