Rsync Options: Devices, Specials, Times, and Access Times

in some circumstances (see also the --numeric‐ids option for a full discussion). --devices This option causes rsync to transfer character and block device files to the remote system to recreate these devices. If the re‐ ceiving rsync is not being run as the super‐user, rsync silently skips creating the device files (see also the --super and --fake‐ super options). By default, rsync generates a "non‐regular file" warning for each device file encountered when this option is not set. You can si‐ lence the warning by specifying --info=nonreg0. --specials This option causes rsync to transfer special files, such as named sockets and fifos. If the receiving rsync is not being run as the super‐user, rsync silently skips creating the special files (see also the --super and --fake‐super options). By default, rsync generates a "non‐regular file" warning for each special file encountered when this option is not set. You can silence the warning by specifying --info=nonreg0. -D The -D option is equivalent to "--devices --specials". --copy‐devices This tells rsync to treat a device on the sending side as a regu‐ lar file, allowing it to be copied to a normal destination file (or another device if --write‐devices was also specified). This option is refused by default by an rsync daemon. --write‐devices This tells rsync to treat a device on the receiving side as a regular file, allowing the writing of file data into a device. This option implies the --inplace option. Be careful using this, as you should know what devices are present on the receiving side of the transfer, especially when running rsync as root. This option is refused by default by an rsync daemon. --times, -t This tells rsync to transfer modification times along with the files and update them on the remote system. Note that if this option is not used, the optimization that excludes files that have not been modified cannot be effective; in other words, a missing -t (or -a) will cause the next transfer to behave as if it used --ignore‐times (-I), causing all files to be updated (though rsync’s delta‐transfer algorithm will make the update fairly efficient if the files haven’t actually changed, you’re much better off using -t). A modern rsync that is using transfer protocol 30 or 31 conveys a modify time using up to 8‐bytes. If rsync is forced to speak an older protocol (perhaps due to the remote rsync being older than 3.0.0) a modify time is conveyed using 4‐bytes. Prior to 3.2.7, these shorter values could convey a date range of 13‐Dec‐1901 to 19‐Jan‐2038. Beginning with 3.2.7, these 4‐byte values now con‐ vey a date range of 1‐Jan‐1970 to 7‐Feb‐2106. If you have files dated older than 1970, make sure your rsync executables are up‐ graded so that the full range of dates can be conveyed. --atimes, -U This tells rsync to set the access (use) times of the destination files to the same value as the source files. If repeated, it also sets the --open‐noatime option, which can help you to make the sending and receiving systems have the same access times on the transferred files without needing to run rsync an extra time after

This section details rsync options including '--devices' for transferring device files, '--specials' for special files, and '-D' as a shortcut for both. '--copy-devices' and '--write-devices' allow treating devices as regular files for copying. '--times' or '-t' transfers modification times, crucial for file update optimization. '--atimes' or '-U' sets destination access times to match the source, with a repeated use also setting '--open-noatime' to ensure consistent access times between systems without needing an extra rsync run.