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mkdir test
echo $1
echo $2

It appears that following two commands do the same things. Are they the same? If not, how could I alter my example to show the difference?

cat | bash -s hi bye
source hi bye
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Is this a homework question? – mdpc Jun 10 '13 at 18:18
@mdpc… – StuartHa Jun 10 '13 at 22:31

1 Answer 1

up vote 4 down vote accepted

The difference will be if you are trying to alter the environment of your current shell (i.e. set a shell or environment variable). For example

$ cat
$ unset myVariable; source; echo ${myVariable:-null}
$ unset myVariable; bash -s <; echo ${myVariable:-null}

This is what source is for: evaluate a script in the current shell. When you launch a new bash process, it cannot alter the parent process's environment.

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