Is there an ignore command for git like there is for svn?

Question

I am a new user to git and I am starting a new project. I have a bunch of dot files that I would like to ignore. Is there an ignore command for git

Answer 1

for names not present in the working copy or repo:

echo /globpattern >> .gitignore

or for an existing file (sh type command line):

echo /$(ls -1 file) >> .gitignore   # I use tab completion to select the file to be ignored  
git rm -r --cached file             # if already checked in, deletes it on next commit