dupfinder

A simple commandline utility for finding duplicate files by comparing file attributes and file data, whilst also offering an option to merge duplicate files into a single, common file through use of hardlinks.

Building

dupfinder can be built for Windows and Unix, and consists of a singular source file (main.c)

Windows:

• Open dupfinder.sln in Visual Studio and hit build

Linux:

• gcc -o dupfinder main.c

• For portability, the following options can be defined if you get build errors by default:
  • -DNO_STRUCT_STAT_ST_TIM: struct timespec stat::st_{amc}tim doesn't exist
  • -DHAVE_STRUCT_STAT_ST_TIMESPEC: struct timespec stat::st_{amc}timespec exists
  • -DHAVE_STRUCT_STAT_ST_TIMENSEC: <unsigned ?> stat::st_{amc}timensec exists
  • -DNO_STRUCT_DIRENT_D_TYPE: unsigned char dirent::d_type doesn't exist

Usage

To prevent accidental use, dupfinder operates in a sort-of dry-run mode by default. In this mode, it will scan directories and files, before printing the groups of identical files it wants to link to each other like this:

$ dupfinder /usr/include
dupfinder: info: scanning: '.'...
dupfinder: info: scanning: 'yajl/'...
dupfinder: info: scanning: 'xorg/'...
dupfinder: info: scanning: 'xcb/'...
[...]
group:["cygwin/icmp.h","icmp.h"]
group:["w32api/txctx.h","w32api/mtsgrp.h","w32api/mtsevents.h"]
group:["w32api/scardsrv.h","w32api/sspsidl.h","w32api/scardmgr.h","w32api/scarddat.h"]
group:["python3.5m/pgen.h","python2.7/pgen.h","python3.7m/pgen.h","python3.6m/pgen.h"]
group:["python3.7m/enumobject.h","python3.6m/enumobject.h","python3.5m/enumobject.h","python2.7/enumobject.h"]
group:["python2.7/metagrammar.h","python3.5m/metagrammar.h","python3.7m/metagrammar.h","python3.6m/metagrammar.h"]
group:["python3.6m/bltinmodule.h","python3.5m/bltinmodule.h","python3.7m/bltinmodule.h"]
[...]
group:["gpgrt.h","gpg-error.h"]

saved_disk_inode: 91
total_disk_inode: 4714
saved_disk_space: 272.23KiB
total_disk_space: 83.30MiB

To automatically merge these groups into the same inode, you must run dupfinder -P /usr/include (the -P mirroring ln(1)'s -P argument that is also used to create hardlinks).

Additionally, the saved_disk_inode: NNN tells you how many INodes can/were freed via file merging, and saved_disk_space: NNN tells you how much file space can/was freed.