99 lines
1.8 KiB
Text
99 lines
1.8 KiB
Text
|
.TH SNAP 4
|
||
|
|
.SH NAME
|
||
|
|
snap, snapfs \- create and mount process snapshots
|
||
|
|
.SH SYNOPSIS
|
||
|
|
.B snap
|
||
|
|
[
|
||
|
|
.B -o
|
||
|
|
.I file
|
||
|
|
]
|
||
|
|
.I pid...
|
||
|
|
.PP
|
||
|
|
.B snapfs
|
||
|
|
[
|
||
|
|
.B -a
|
||
|
|
]
|
||
|
|
[
|
||
|
|
.B -m
|
||
|
|
.I mtpt
|
||
|
|
]
|
||
|
|
.I file...
|
||
|
|
.SH DESCRIPTION
|
||
|
|
.I Snap
|
||
|
|
and
|
||
|
|
.I snapfs
|
||
|
|
allow one to save and restore (static) process images,
|
||
|
|
usually for debugging
|
||
|
|
on a different machine or at a different time.
|
||
|
|
.PP
|
||
|
|
.I Snap
|
||
|
|
writes a snapshot
|
||
|
|
(see
|
||
|
|
.IR snap (6))
|
||
|
|
of the named processes to
|
||
|
|
.I file
|
||
|
|
(default standard output).
|
||
|
|
If
|
||
|
|
.I pid
|
||
|
|
is a text string
|
||
|
|
rather than a process id,
|
||
|
|
.I snap
|
||
|
|
will save all processes with
|
||
|
|
that name that
|
||
|
|
are owned by the current user.
|
||
|
|
Both memory and text images are saved.
|
||
|
|
.PP
|
||
|
|
.I Snapfs
|
||
|
|
is a file server that
|
||
|
|
recreates the
|
||
|
|
.B /proc
|
||
|
|
directories for the processes in the snapshot.
|
||
|
|
By default, it mounts the new directories
|
||
|
|
into
|
||
|
|
.B /proc
|
||
|
|
before the current entries.
|
||
|
|
The
|
||
|
|
.B -m
|
||
|
|
option can be used to specify
|
||
|
|
an alternate mountpoint,
|
||
|
|
while
|
||
|
|
.B -a
|
||
|
|
will cause it to mount the new directories
|
||
|
|
after the current entries.
|
||
|
|
.SH EXAMPLE
|
||
|
|
Suppose
|
||
|
|
.I page
|
||
|
|
has hung viewing Postscript on your terminal, but the author is gone for the rest of
|
||
|
|
the month and you want to make sure the process
|
||
|
|
is still around for debugging on his return.
|
||
|
|
You can save the errant processes with
|
||
|
|
.IP
|
||
|
|
.EX
|
||
|
|
snap -o page.snap `{psu | awk '$NF ~ /page|gs/ {print $2}'}
|
||
|
|
.EE
|
||
|
|
.PP
|
||
|
|
When the author returns, he can add the process images to his name space
|
||
|
|
by running
|
||
|
|
.IP
|
||
|
|
.EX
|
||
|
|
snapfs page.snap
|
||
|
|
.EE
|
||
|
|
.PP
|
||
|
|
and then use a conventional
|
||
|
|
debugger to debug them.
|
||
|
|
.SH SOURCE
|
||
|
|
.B /sys/src/cmd/snap
|
||
|
|
.SH SEE ALSO
|
||
|
|
.IR acid (1),
|
||
|
|
.IR db (1),
|
||
|
|
.IR proc (3),
|
||
|
|
.IR snap (6)
|
||
|
|
.SH BUGS
|
||
|
|
The snapshots take up about as much disk space
|
||
|
|
as the processes they contain did memory.
|
||
|
|
Compressing them when not in use is recommended,
|
||
|
|
as is storing them on a rewritable disk.
|
||
|
|
.PP
|
||
|
|
.I Pid
|
||
|
|
as a non-numeric string is unimplemented; it has to be a number.
|