NAME

lock − run a command under lock

SYNOPSIS

­lock [ ­-w ] ­lockfile [ ­command [ ­argument ...  ] ]

DESCRIPTION

­Lock runs ­command (default rc) with ­arguments while holding ­lockfile open and (over)writing at least one byte each minute to keep the exclusive-access lock alive.  If ­lockfile doesn’t already have the exclusive-access bit set in its mode, the exclusive-access bits are set in its mode and qid.type. 

Under -w, ­lock waits for exclusive access to ­lockfile instead of just trying once. 

­Lock sets ­/env/prompt to contain the name of the lock file. 

EXAMPLES

Build a replica(1) database while preventing collisions with other occurrences.

cd /sys/lib/dist
lock scan.lock replica/scan $dist/sources.replica

SOURCE

­/sys/src/cmd/lock.c

SEE ALSO

intro(5), stat(5)

Plan 9  —  December 28, 2008