Replace one character with another in Bash

I need to be able to do is replace a space () with a dot (.) in a string in bash.

I think this would be pretty simple, but I'm new so I can't figure out how to modify a similar example for this use.

Use inline shell string replacement. Example:

foo="  "

# replace first blank only
bar=${foo/ /.}

# replace all blanks
bar=${foo// /.}

See http://tldp.org/LDP/abs/html/string-manipulation.html for more details.

You could use tr, like this:

tr " " .

Example:

# echo "hello world" | tr " " .
hello.world

From man tr:

DESCRIPTION
     Translate, squeeze, and/or delete characters from standard input, writ‐ ing to standard output.

In bash, you can do pattern replacement in a string with the ${VARIABLE//PATTERN/REPLACEMENT} construct. Use just / and not // to replace only the first occurrence. The pattern is a wildcard pattern, like file globs.

string='foo bar qux'
one="${string/ /.}"     # sets one to 'foo.bar qux'
all="${string// /.}"    # sets all to 'foo.bar.qux'