grep -e 'attrib1' -e 'attrib3' file

From the man page :

-e PATTERN, --regexp=PATTERN
Use PATTERN as the pattern. This can be used to specify multiple search patterns, or to protect a pattern beginning with a hyphen (-). (-e is specified by POSIX.)

Edit : Alternatively , you can save patterns in a file and use the -f option :

aman@aman-VPCEB14EN:~$ cat>patt
attrib1
attrib3

aman@aman-VPCEB14EN:~$ grep -f patt test
attrib1:  someval11
attrib3:  someval13
attrib1:  someval21
attrib3:  someval23
attrib1:  someval31
attrib3:  someval33

Very simple command:

 bash> grep  "attrib1\|attrib3" <file.name>
attrib1:  someval11
attrib3:  someval13
attrib1:  someval21
attrib3:  someval23
attrib1:  someval31
attrib3:  someval33

Also egrep;

egrep "pattern1|pattern2|pattern3" file

This works, with GNU grep 2.6.3

grep "attrib[13]"

or

 grep "^[^0-9]*[13]:"

It depends on the shell you are into. grep -iw 'patter1\|patter2\|pattern3' works on bash shell where as it doesn't work on korn shell. For korn shell we might have to try grep -e pattern1 -e patter2 and so on.