head [options] <file_name>
By default, head will print the first 10 lines of its input to the standard output. The number of lines printed may be changed with a command line option. The following example shows the first 20 lines of filename:
head -n 20 filename
This displays the first 5 lines of all files starting with foo:
head -n 5 foo*
Most versions allow omitting the n and just let you say -5. GNU head allows negative arguments for -n option, meaning to print all but the last - argument value counted - lines of each input file.
-c <x number of bytes> Copy first x number of bytes.
Many early versions of Unix did not have this command, and so documentation and books had sed do this job:
sed 5q foo
This says to print every line (implicit), and quit after the fifth.