Ahem, this won't work in AIX either. The only place where you can skip the "$" and have the variable expanded anyway is inside double-brackets:

Code:

var=1
(( var = var + 1 ))
print - $var

This is standard ksh and it will definitely work in Linux-ksh as well as in AIX-ksh.


The rule is: the comparison will work, regardless if the variable is quoted or not. The problem one avoids with quoting variables is this: if the variable contains whitespace, the expanded variable will lead to a syntax error once it is expanded, because the shell treats the resulting expanded value as two (or more words):

Code:

typeset var="abc"
if [ $var == abc ] ; then         # this is first expanded to
if [ abc == abc ]  ; then         # which is a legal statement

typeset var="abc def"
if [ $var == abc ] ; then                 # this is first expanded to
if [ abc def == abc ]  ; then             # which is NOT a legal statement, but
if [ "$var" == "abc" ] ; then             # this is first expanded to
if [ "abc def" == "abc" ]  ; then         # which is legal again

You might want to do that because otherwise it would be misleading, but it is not required at all. The OS only cares for the shebang and the executable flag and whcih extension the file has doesn't matter at all.

In AIX "/bin" is a link to "/usr/bin". This is one of my 7.1.3-testsystems:

Code:

# ls -l /bin
lrwxrwxrwx    1 bin      bin               8 Feb  5 09:27 /bin -> /usr/bin

According to the POSIX documents this ("-n <number>") is the modern and suggested form and should be used anyway. If at all the old syntax is only supported for backwards compatibility purposes.

I hope this helps.

bakunin