Date: Thu, 25 Apr 2024 09:50:11 GMT From: Mateusz Piotrowski <0mp@FreeBSD.org> To: src-committers@FreeBSD.org, dev-commits-src-all@FreeBSD.org, dev-commits-src-main@FreeBSD.org Subject: git: 177ba183076b - main - sync.8: Document that the "sync dance" is not a thing Message-ID: <202404250950.43P9oB6P043000@gitrepo.freebsd.org>
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The branch main has been updated by 0mp: URL: https://cgit.FreeBSD.org/src/commit/?id=177ba183076bd6fe6b29b1d657b954cca256506b commit 177ba183076bd6fe6b29b1d657b954cca256506b Author: Mateusz Piotrowski <0mp@FreeBSD.org> AuthorDate: 2024-04-23 14:12:45 +0000 Commit: Mateusz Piotrowski <0mp@FreeBSD.org> CommitDate: 2024-04-25 09:49:50 +0000 sync.8: Document that the "sync dance" is not a thing People still believe that it is essential to run sync(8) a couple of times before a reboot/halt. Document that this has not been necessary for a long time now. Reviewed by: imp, bcr, Pau Amma <pauamma@gundo.com> MFC after: 3 days Differential Revision: https://reviews.freebsd.org/D33233 --- bin/sync/sync.8 | 30 +++++++++++++++++++++++++++++- 1 file changed, 29 insertions(+), 1 deletion(-) diff --git a/bin/sync/sync.8 b/bin/sync/sync.8 index d7a11c9fd217..fcd07ca72240 100644 --- a/bin/sync/sync.8 +++ b/bin/sync/sync.8 @@ -26,7 +26,7 @@ .\" OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF .\" SUCH DAMAGE. .\" -.Dd May 31, 1993 +.Dd April 25, 2024 .Dt SYNC 8 .Os .Sh NAME @@ -69,3 +69,31 @@ A .Nm utility appeared in .At v4 . +.Pp +On systems older than +.Bx 4.0 , +commands like +.Xr reboot 8 +and +.Xr halt 8 +were unavailable. +The shutdown procedure involved running +.Nm , +waiting for the lights to stop, +and turning off the machine. +.Pp +Issuing three separate +.Nm +commands (one line each) was a placebo that would generally suffice in +.At v7 +machines that were otherwise quiesced systems. +It replaced the one-per-line +.Nm +as a substitute for waiting. +.Pp +.Bx 4.0 +introduced +.Xr reboot 2 +and +.Xr sync 2 +which rendered this trick obsolete.
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