A worse implementation of gnu head but in rust.
This really sucks right now because I am basically loading the entire file into memory in order to support negative NUM values. Its an interesting problem because you want to stream the file and load it line-by-line or byte-by-byte but with this approach you can't know how many lines a file has before hand.
Either way it mostly works...
Usage: head [OPTIONS]... [FILE]...
Print the first 10 lines of each FILE to standard output.
With more than on FILE, precede each with a header giving the file name.
With no FILE, or when FILE is -, read standard input.
Arguments:
[FILE]... The file(s) to print
Options:
-c, --bytes <[-]NUM> Print the first NUM bytes of each file;
with the leading '-', print all but the last
NUM bytes of each file
-n, --lines <[-]NUM> Print the first NUM lines instead of the frist 10;
with the leading '-', print all the but the last
NUM lines of each file [default: 10]
-q, --quiet Never print headers giving file names
-v, --verbose Always print headers giving file names
-z, --zero-terminated Line delimiter is NUL, not newline
-h, --help Print help
-V, --version Print version
NUM may have a multiplier suffix:
b 512, kB 1000, K 1024, MB 1000*1000, M 1024*1024,
GB 1000*1000*1000, G 1024*1024*1024