ls thefile
split -b 500k !$ !$.
split -b 500k !$ !$.split.
!! | xargsi -t split {} ~+1/{}. -d -a 3 -b 500k/10m
# space ok!

 !! | split -l 1000 - tmp.split.
 perl -e '$lmt=30; $pre="tmp.split."; $si="aa"; foreach (1..$lmt){ print "$pre$si\n"; $si++} '

 ls tmp.split.?? | doeach.pl fileh ftt0 @~cat @_@~
 rm tmp.split.??

$ jot 10 | split -l 3 -
$ ls xa? | doeach.pl echo @~cat @_@~

echo `cat xaa`
1 2 3

echo `cat xab`
4 5 6

echo `cat xac`
7 8 9

echo `cat xad`
10

$ split --help
 Usage: split [OPTION] [INPUT [PREFIX]]
Output fixed-size pieces of INPUT to PREFIXaa, PREFIXab, ...; default
PREFIX is `x'.  With no INPUT, or when INPUT is -, read standard input.

Mandatory arguments to long options are mandatory for short options too.
  -a, --suffix-length=N   use suffixes of length N (default 2)
  -b, --bytes=SIZE        put SIZE bytes per output file
  -C, --line-bytes=SIZE   put at most SIZE bytes of lines per output file
  -l, --lines=NUMBER      put NUMBER lines per output file
      --verbose           print a diagnostic to standard error just
                            before each output file is opened
      --help     display this help and exit
      --version  output version information and exit

SIZE may have a multiplier suffix: b for 512, k for 1K, m for 1 Meg.

-d, --numeric-suffixes
       use numeric suffixes instead of alphabetic

-a, --suffix-length=N
       use suffixes of length N (default 2)

-b, --bytes=SIZE
       put SIZE bytes per output file