Question: What does /dev/disk/by-pathdescribe? And where is this documented?Going through the meaning of what is displayed in the folders /dev/disk/by- I've got that far, and I wonder is this correct?by-id → based upon the serial number of the hardware devicesby-label → Whatever name was set manually for this diskby-path → ?!by-uuid →  Universal Unique Identifier: a uniquely created string to identify the disk [done so through the system][Note: I work on GNU/Linux Debian 7, Crunchbang, if this matters…]
understanding /dev/disk/by- folders
linux;mount;fstab;uuid
Mountpoint /dev is devtmpfs filesystem and managed by udev completely.So for details we have to go to udev configuration.2 udev rules are handling this typically$ grep -ri '/dev/disk' /usr/lib/udev/rules.d//usr/lib/udev/rules.d/60-persistent-storage.rules:# persistent storage links: /dev/disk/{by-id,by-uuid,by-label,by-path}/usr/lib/udev/rules.d/13-dm-disk.rules:# These rules create symlinks in /dev/disk directory.60-persistent-storage.rules mentions# by-path (parent device path)ENV{DEVTYPE}==disk, DEVPATH!=*/virtual/*, IMPORT{builtin}=path_idENV{DEVTYPE}==disk, ENV{ID_PATH}==?*, SYMLINK+=disk/by-path/$env{ID_PATH}ENV{DEVTYPE}==partition, ENV{ID_PATH}==?*, SYMLINK+=disk/by-path/$env{ID_PATH}-part%nFinally ID_PATH is a unique identificator for a device based on it's physical HW location / connection (eg. something like ID_PATH=pci-0000:02:04.0-scsi-0:0:0:0).ID_PATH comes from builtin udev program called path_id (eg. for /sys/block/sdc)$ udevadm test-builtin path_id /sys/block/sdccalling: test-builtin=== trie on-disk ===tool version:          204file size:         5632867 bytesheader size             80 bytesstrings            1260755 bytesnodes              4372032 bytesload module indexID_PATH=pci-0000:00:14.0-usb-0:1:1.0-scsi-0:0:0:0ID_PATH_TAG=pci-0000_00_14_0-usb-0_1_1_0-scsi-0_0_0_0We can relate it todrwxr-xr-x 6 root root 0 Aug 15 02:30 /sys/devices/pci0000:00/0000:00:14.0/usb1/1-1/1-1:1.0/Ultimately, if anybody is interested in details consult the source codehttp://cgit.freedesktop.org/systemd/systemd/tree/src/udev/udev-builtin-path_id.c