Print the first few lines (default is 10) of one or more files. If files is missing or -, read from standard input. With more than one file, print a header for each file.
Print first num bytes or, if num is followed by b, k, or m, first num 512-byte blocks, 1-kilobyte blocks, or 1-megabyte blocks.
Display help and then exit.
Print first num lines. Default is 10.
Quiet mode; never print headers giving filenames.
Print filename headers, even for only one file.
Output version information and then exit.
Display the first 20 lines of phone_list:
head -20 phone_list
Display the first 10 phone numbers having a 202 area code:
grep '(202)' phone_list | head