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join-utils

Command line utilities for joining text files similary to the UNIX join program with some extra functionality

This repository contains 3 different variations on the UNIX / GNU 'join' command written in C# and C++ with the following additional functionality:

  • numeric_join.cs / numeric_join.cpp: the join field is considered to be numeric (a 64-bit signed integer) and files are expected to be sorted in numeric order; this is supposed to save the extra sort step as the original join command only expects files sorted in dictionary order

  • hashjoin.cs: instead of requiring sorted input, it uses a hashtable to join files; the hashtable is built from the first file (so that has to be of moderate size), and the second file is processed in a streaming fashion; useful if one of the files is very large

  • hashjoin_multiple.cs: similar to the previous, but multiple hashtables can be built from multiple files to perform several join steps in one pass

All were tested on Linux using the Microsoft csc compiler (version 2.6), and the Mono runtime (version 5.10). Compiling should be straightforward from the command line using the csc command (e.g. 'csc hashjoin.cs'); for Visual Studio, just create an empty project and add the corresponding file. The C++ version was tested with g++, and requires C++11 (e.g. 'g++ -o numjoin numeric_join.cpp -std=gnu++11 -O3'). All programs have a short description in the source and display usage instructions with the '-h' command line option. Most options follow those of the original 'join' command, where possible.

how to compile a stand-alone executable for Linux

Mono's mkbundle command can be used to create an ''stand-alone'' binary that can be run without relying on the Mono / .NET runtime. To convert the .exe to such native Linux binary, use the following:

mkbundle --i18n none --static -o numeric_join numeric_join.exe /usr/lib/mono/4.5/mscorlib.dll

The result will likely be quite large (~5-10 MB), as this embeds part of the Mono runtime and libraries together with the compiled code. This can be moved to another Linux machine without Mono installed and run. Note that this actually does not produce a statically linked binary: the result will still use basic dynamic libraries on the system, mainly libc, libm and such. Thus, these need to be compatible.