find and tar command

to find a file named myfile

        find * -name myfile  -print

        find * -name "*.tex"  -print

to find files larger than n*512 bytes type

        find * -size +n -print

to find files smaller than n*512 bytes type

        find * -size -n -print

To tar and compress:

    tar -cvf archive.tar *.dat
or
    tar -cvf archive.tar mydirectory/*

then remove original files or directory. To compress:

    gzip myfile  (gunzip when uncompressing)

Note:

    tar -xvf filename.tar

to restore the orignal files structures. There is also

    tar -tvf filename.tar

to get a table of contents.