dbrowcount man page

dbrowcount — count the number of rows in an Fsdb stream

Description

Count the number of rows and write out a new fsdb file with one column (n) and one value: the number of rows. This program is a strict subset of dbcolstats.

Although there are other ways to get a count of rows ("dbcolstats", or "dbrowaccumulate -C 1" and some processing), counting is so common it warrants its own command. (For example, consider how often "wc -l" is used in regular shell scripting.) There are some gross and subtle differences, though, in that "dbrowcount" doesn't require one to specify a column to search, and it also doesn't look for and skip null data items.

Options

No program-specific options.

This module also supports the standard fsdb options:

-d
Enable debugging output.
-i or --input InputSource
Read from InputSource, typically a file name, or "-" for standard input, or (if in Perl) a IO::Handle, Fsdb::IO or Fsdb::BoundedQueue objects.
-o or --output OutputDestination
Write to OutputDestination, typically a file name, or "-" for standard output, or (if in Perl) a IO::Handle, Fsdb::IO or Fsdb::BoundedQueue objects.
--autorun or --noautorun
By default, programs process automatically, but Fsdb::Filter objects in Perl do not run until you invoke the run() method. The "--(no)autorun" option controls that behavior within Perl.
--help
Show help.
--man
Show full manual.

Sample Usage

Input

#fsdb      absdiff
0
0.046953
0.072074
0.075413
0.094088
0.096602
#  | /home/johnh/BIN/DB/dbrow 
#  | /home/johnh/BIN/DB/dbcol event clock
#  | dbrowdiff clock
#  | /home/johnh/BIN/DB/dbcol absdiff

Command

cat data.fsdb | dbrowcount

Output

#fsdb n
6
#  | /home/johnh/BIN/DB/dbrow 
#  | /home/johnh/BIN/DB/dbcol event clock
#  | dbrowdiff clock
#  | /home/johnh/BIN/DB/dbcol absdiff

Input 2

As another example, this input produces the same output as above in "dbrowcount", but different output in "dbstats":

#fsdb      absdiff
-
-
-
-
-
-
#  | /home/johnh/BIN/DB/dbrow 
#  | /home/johnh/BIN/DB/dbcol event clock
#  | dbrowdiff clock
#  | /home/johnh/BIN/DB/dbcol absdiff

See Also

dbcolaccumulate(1), dbcolstats(1), Fsdb(3)

Info

2016-09-05 perl v5.24.0 User Contributed Perl Documentation