LOCK(1)                                                   LOCK(1)

     NAME
          lock - run a command under lock

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

     DESCRIPTION
          Lock runs command (default `rc') with arguments while hold-
          ing 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)