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dbmerge2 - Man Page

merge exactly two inputs in sorted order based on the the specified columns


    dbmerge2 --input A.fsdb --input B.fsdb [-T TemporaryDirectory] [-nNrR] column [column...]

   cat A.fsdb | dbmerge2 --input B.fsdb [-T TemporaryDirectory] [-nNrR] column [column...]


Merge exactly two sorted input files, producing one sorted result. Inputs can both be specified with --input, or one can come from standard input and the other from --input.

Inputs must have identical schemas (columns, column order, and field separators).

Dbmerge2 consumes a fixed amount of memory regardless of input size.

Although described above as a command line too, the command line version of dbmerge2 is not installed by default. Dbmerge2 is used primarily internal to perl; dbmerge(1) is the command-line tool for user use.

Warning: we do not verify that each input is actually sorted. In correct merge results will occur if they are not.


General option:

--saveoutput $OUT_REF

Save output writer (for integration with other fsdb filters).

<-T TmpDir>

where to put tmp files. Also uses environment variable TMPDIR, if -T is  not specified. Default is /tmp.

Sort specification options (can be interspersed with column names):

-r or --descending

sort in reverse order (high to low)

-R or --ascending

sort in normal order (low to high)

-n or --numeric

sort numerically

-N or --lexical

sort lexicographically

This module also supports the standard fsdb options:


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.

--header H

Use H as the full Fsdb header, rather than reading a header from then input.


Show help.


Show full manual.

Sample Usage


File a.fsdb:

    #fsdb cid cname
    11 numanal
    10 pascal

File b.fsdb:

    #fsdb cid cname
    12 os
    13 statistics


    dbmerge2 --input a.fsdb --input b.fsdb cname


    cat a.fsdb | dbmerge2 --input b.fsdb cname


    #fsdb      cid     cname
    11 numanal
    12 os
    10 pascal
    13 statistics
    #  | dbmerge2 --input a.fsdb --input b.fsdb cname

See Also

dbmerge(1), dbsort(1), Fsdb(3)

Referenced By


2024-07-01 perl v5.40.0 User Contributed Perl Documentation