I have file1 and file2:

file1:

11 xxx kksd ...
22 kkk kdsglg...
33 sss kdfjdksa...
44 kdsf dskjfkas ...
hh kdkf kdkkd..
jg dkf dfkdk ...
...

file2:

jg
22
hh
...

I need to check each line of file1. if the field one is in file2, I will keep it; if not, the whole line will be discarded. The result file will be:

jg dkf dfkdk ...
22 kkk kdsglg...
hh kdkf kdkkd..
...

please tell me how I can do this, thanks!