3 snap \- process snapshots
5 Process snapshots are used to
6 save a process image for debugging on
7 another machine or at another time.
8 They are like old Unix core dumps but
9 can hold multiple process images and
12 The first line of a snapshot begins with the prefix
13 ``process snapshot'' and often contains
14 other information as well, such as creation time,
15 user name, system name, cpu type, and kernel type.
16 This information is intended for humans, not programs.
17 Programs reading snapshots should only
18 check that this line begins with the specified prefix.
20 Throughout the rest of the snapshot, decimal strings are
21 always right-justified, blank-padded to at least 11 characters,
22 and followed by a single space character.
24 The rest of the snapshot is one or more records,
25 each of which begins with a one-line header.
26 This header is a decimal process id followed by
27 an identification string, which denotes the type of
41 are all formatted as a decimal number
46 This data is the contents of the file
47 of the same name found in
54 sections is not as simple.
55 These sections contain one or more page descriptions.
56 Each describes a one kilobyte page of data.
57 If the section is not a multiple of a kilobyte in size,
58 the last page will be shorter.
59 Each description begins with a one-byte
63 then it is followed by
64 a page of binary data.
67 then the data is understood to be zeros,
73 then it is followed by two decimal strings
77 indicating that this page is the same
83 This data must have been previously
84 described in the snapshot, and the offset
85 must be a multiple of a kilobyte.
87 It is not guaranteed that any of the sections
88 described above be in a process snapshot,
89 although the snapshot quickly becomes useless when
92 Memory and text images may be incomplete.
93 The memory or text file for a given process
94 may be split across multiple disjoint sections