rcs: Stamp resolution
3.2 Stamp resolution
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Regarding RCS, recorded timestamps come into play in two places:
• The ‘delta’ production of the file format grammar includes
component ‘date’ (⇒comma-v grammar). The recorded
information has second (whole number) resolution.
• The metadata of a file on the filesystem usually includes its
“modification time”. The resolution of this information depends on
the capabilities of the filesystem; modern ones — e.g., ext4
(https://en.wikipedia.org/wiki/Ext4) — tend to support subsecond
(fractional) resolution.
Historically, up through version 5.9.4, RCS behaved “agnostically”
with respect to the subsecond component of the file modification time,
relying on the operating system and filesystem to take care of things at
whatever resolution was available at the time, with the single exception
of the ‘-T’ option (⇒Misc common options). In the presence of
this option, RCS would:
• (reading) Ignore the subsecond component.
• (writing) Specify 0 as the subsecond component.
For versions after 5.9.4, if the filesystem supports it, RCS reads
and writes file modification time with subsecond resolution, given the
‘-T’ option.
It’s important to keep in mind that by design, the delta ‘date’
component is limited to second resolution, so subsecond resolution is
only guaranteed for operations where the file modification time
originates from a file actually existing on the filesystem (i.e., via
the ‘stat(2)’ system call).
Info Catalog
rcs: File format
rcs: Hacking
rcs: Still missing