Tru64 v5.1 Rev.732 .profile $PATH question

[YLTan]

What does "-" implies in the .profile path??
PATH=$HOME/bin:${PATH:-/usr/bin:.}

Removing the "-" will cause bad substitution.

Why Tru64 have its part of the PATH to be substitute as ${PATH:-/usr/bin:.}

Any implication if I move the . current dir. to outside the curly bracket??

[rachel_11 · Accepted solution]

Hello,

Look at man for ksh.
The syntax of ${parameter:-word} is, if parameter not set or null use word.
for example:
$ echo ${KUKI}
sh: KUKI: Parameter not set.
$ echo ${KUKI:-abcdef}
abcdef

[Stephen Carpenter]

The :- performs a conditional substitution. See sh(1b):

${ variable:-string }
If the variable is set and is not null, substitute the value of variable in place of this expression. Otherwise, replace this expression with the value of string.

In the .profile the conditional subsitution is used to generate /usr/bin:. if PATH has not yet been set.