Linux and Unix du command
Tells you how much space a file occupies.
du [-a] [-k] [-s] [-d] [-L] [-o] [-r] [-x] directories
|-a||Displays the space that each file is taking up.|
|-k||Write the files sizes in units of 1024 bytes, rather than the default 512-byte units.|
|-s||Instead of the default output, report only the total sum for each of the specified files.|
|-d||Do not cross filesystem boundaries. For example, du -d / reports usage only on the root partition.|
|-L||Process symbolic links by using the file or directory which the symbolic link references, rather than the link itself.|
|-o||Do not add child directories' usage to a parent's total. Without this option, the usage listed for a particular directory is the space taken by the files in that directory, as well as the files in all directories beneath it. This option does nothing if -s is used.|
|-r||Generate messages about directories that cannot be read, files that cannot be opened, and so forth, rather than being silent (the default).|
|-x||When evaluating file sizes, evaluate only those files that have the same device as the file specified by the file operand.|
|directories||Specifies the directory or directories.|
du -s *.txt
Would report the size of each txt file in the current directory. Below is an example of the output.
du -sh *.txt
Display the size of the txt files in a friendly size format listing as well as the total capacity of all the files combined.