Shell Programming and Scripting

ADD
john
mickey

DROP
matt
sam

john
mickey

matt
sam

awk '/ADD/{x="F"++i;}{print > x;}' file1

awk '$1=="ADD"{f="F1"; next} $1=="DROP"{f="F2"; next} NF{print >f}' file1

awk '/^(ADD|DROP)/{suffix=$1; next} NF{print >(FILENAME "." suffix)}' file1

Split a text file into pieces, i.e. groups of lines:

        1) split, standard, but many variants exist in systems
           split a file into pieces

        2) csplit, standard
           split a file into sections determined by context lines

        3) r3split (local, Ratio, iRregular, Random,
           specify numbers in groups, percentage, random set of lines)

        4) pasplit (local, approximate, fast parallel-process split)

        5) mmsplit (local, multi-method, by number of lines, groups, pattern))

        6) scatter (local, regular number, like dealing a deck of playing cards)

        7) ppt-split (local, csplit with perl patterns, Perl Power Tools)
           https://github.com/briandfoy/PerlPowerTools/blob/master/bin/split 
           2016.08.02

        8) split_at_colchange (missing-text/local, add empty line when column changes)
        http://www1.cuni.cz/~obo/textutils/

        9) gate (local, Group And Transfer Entries, into files by field pattern)

        10) fsplit (local, split Fortran-77 into files by module name)

        12) mfs (local, split Fortran routines into files by name, handles "module")

        13) xsplit (local, explicit list of line numbers to files)

        14) nsplit (local, into "s" parts - bytes, not lines)

        15) bsplit (3rd/local, binary file with dd, originally named fsplit)

        16) f90split (3rd/local, split Fortran-90 source)

...
pl " Results, csplit, second file:"
csplit --quiet --prefix=f -z $FILE '/^[A-Z]/' '{*}'
head f01

pl " Results, ppt-split, first file:"
ppt-split -p '^[A-Z]' $FILE
head x.aab

-----
 Results, csplit, second file:
DROP
matt
sam

-----
 Results, ppt-split, first file:
ADD
john
mickey

LC_ALL=C awk '/[A-Z]/{F="file."$1;next}NF{print > F}' file1

LC_ALL=C awk '/[A-Z]/{F="F"++i;next}NF{print > F}' file

awk '$1=="ADD"{f="F1"; next} $1=="DROP"{f="F2"; next} NF{print >f}'   Input_file
awk: (FILENAME=Input_file FNR=1) fatal: expression for `>' redirection has null string value

cfcgshg
hjgftyv
ADD
john
mickey

DROP
matt
sam

awk '$1=="ADD"{f="F1"; next} $1=="DROP"{f="F2"; next} NF && f{print >f}'   Input_file

awk '{f=$1=="ADD"?"F1":($1=="DROP"?"F2":f)} NF && f && $1 != "DROP" && $1 != "ADD"{print > f}'   Input_file