Bash Shell: for loop returns different values

Question

$values contains a string which I grep from a config file. This string can be eiter: ?, ! or just a string containing words like "foo bar".

values="?"
for value in ${values}
do
    echo "value is ${value}"
done

If I execute the script on local host, the result is:

value is ?

However, if i execute the script from a remote host (using ssh and sudo su - someuser "/tmp/foo.sh"), the result is:

value is 2

Until now, I was not able to find out whats different. Could anyone help please?

I'm guessig that the variable is expanded for some reason. Maybe the other side default shell is not bash? What does 'echo $0' output? — RedX
– RedX, Commented Dec 17, 2013 at 10:18
Whether arguments are expanded or not can depend on whether there is a match in the target directory. I have a script x.sh that echos all its arguments. ./x.sh ?.sh echos 'x.sh' while ./x.sh ?.sl echos '?.sl' because there is no match. — Mzzl
– Mzzl, Commented Dec 17, 2013 at 10:29
Do you have any file called 2 in your remote machine? Note that ls ? returns 2 if you happen to have a file with that name, or -in general- it returns the list of files with one character name. — fedorqui
– fedorqui, Commented Dec 17, 2013 at 10:30

Reinstate Monica Please · Accepted Answer · 2013-12-17 10:29:32Z

3

You need to quote variables, otherwise bash will try to expand $values in the for-header.

values="?"
for value in "${values}"
do
    echo "value is ${value}"
done

? by itself in bash tries to expand to any single character file names in the current directory. e.g.

$ mkdir somedir
$ cd somedir
$ echo ?
?
$ mkdir a
$ echo ?
a 
$ touch {b..z}
$ echo ? 
a b c d e f g h i j k l m n o p q r s t u v w x y z

So depends on what you have on each system, guessing you have a file 2 on the remote host.

answered Dec 17, 2013 at 10:29

Reinstate Monica Please

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3 Comments

RedX Over a year ago

Another option is to set noglob. Read more here

phil Over a year ago

Noglob works. But I dont understand why the shell does not expand the ? character when starting the script locally, but it is expanded if I start the script from a different host.

Reinstate Monica Please Over a year ago

@Phil I'm positive it does expand the character locally, very likely you just don't have any single character files in the directory on your local computer. And default behavior for special characters when that happens is just to display the special character. For example go to an empty directory and echo * and it will actually print *.

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