Do you want to know the size of a directory in Linux? Use the du command.
du -sh
Explanation
The du command estimates the space used by a directory.
The options -sh are (from man du):
-s, --summarize display only a total for each argument -h, --human-readable print sizes in human readable format (e.g., 1K 234M 2G)
To check more than one directory and get the total size of those directories, use
du -sch *
What does the extra option mean?
-c, --total produce a grand total
Include hidden files?
du -sch * .*
Want to know how much disk space has been used?
du -h .