Syntax for if statement

I'm new to unix and the command line and am trying to learn different commands. I have a file (teledir.txt) that contains a name and phone number for 3 different people. I am writing a script that is to take two positional parameters and I typed out how it should behave:

if <name and number exists>; then
     <echo matching line>
elif <name exists>; then
     <echo line>
elif <number exists>; then
     <echo matching line>; then
else 

     <if both name and number were provided, add them to the file>
fi

I declared two variables: name=$1 and number=$2 . But I'm lost on what command to use in the script to see if the name and/or number exists in the other file.

Any pointers?

Hi, try this

if grep -qiw "$var1\|$var2" teledir.txt; then
    echo $var1 or $var2 exist
elif grep -qiw "$var" teledir.txt; then
    echo $var exist
fi