mjhjmtu

I have this command:

sed 's/|.*/ /g' filename 

I would like to know what this command does to the datafile, and if there is another command like awk that can replace that command and perform the same function?

The command sed has many functions. The command you provided in the question is in the form:

sed 's/this/that/g' filename 

This command will read filename and then replace every this in the filename by that. So your command will replace everything after |.* in the filename by an empty spaces.

Let's break down |.*

*
Matches a sequence of zero or more instances of matches for the preceding regular expression, which must be an ordinary character, a special character preceded by , a ., a grouped regexp (see below), or a bracket expression. As a GNU extension, a postfixed regular expression can also be followed by *; for example, a** is equivalent to a*. POSIX 1003.1-2001 says that * stands for itself when it appears at the start of a regular expression or subexpression, but many nonGNU implementations do not support this and portable scripts should instead use * in these contexts. 

.
Matches any character, including newline.

For example:
If filename contain:

|.*2
|.*3
|.*9
|.*10
|.*11
|.*12
|.*24
|.*28
|.*2933

Then the output will be "nothing", because the command sed will replace every |. and the following text represented by * by an empty spaces.

On the other side, if the content of the filename is as follwos:

me|.*2
you|.*3
them|.*9
him|.*10
her|.*11
he|.*12
has|.*24
foo|.*28
bar|.*2933 

Then the output of the command will be

me
you
them
him
her
he
has
foo
bar