dan@hrc.UUCP (Dan Troxel VP) (12/20/88)
What is the difference of the find options ctime and mtime? How will the two different options give me two differnt listings? Or will they? Should I use atime, to be safe, when I do incremental backups every night? -- Dan Troxel VP of Computer Operations @ Handwriting Research Corporation - 2821 E. Camelback Road Suite 600 Phoenix, AZ 85016 WK 1-602-957-8870 HM 1-602-435-1240 UUCP : asuvax!hrc!dan
ark@alice.UUCP (Andrew Koenig) (12/20/88)
In article <388@hrc.UUCP>, dan@hrc.UUCP (Dan Troxel VP) writes: > What is the difference of the find options ctime and mtime? mtime is the last time the file was changed; ctime is the last time the file's inode was changed. Among the operations that will change the inode of a file without changing the file are adding or deleting a link. Thus, for example, renaming a file will change ctime but not mtime. > Should I use atime, to be safe, when I do incremental backups every night? ctime is almost surely best. -- --Andrew Koenig ark@europa.att.com
guy@auspex.UUCP (Guy Harris) (12/21/88)
>What is the difference of the find options ctime and mtime? >How will the two different options give me two differnt listings? >Or will they? >Should I use atime, to be safe, when I do incremental backups every night? The difference between the "find" options is the same as the difference between the "(inode) change time" and "modified time" of a file; see, for instance, STAT(2). The "modified time" is updated when a file's contents are modified, either by writing to the file or by truncating it ("creat", "open" with O_TRUNC, "(f)truncate" for folks lucky enough to have it). The "(inode) change time" is updated whenever the file's inode is changed; this includes changing the link count (e.g. linking to it and, at least on many systems, renaming it), changing the permissions on it, etc.. It also is updated when the file is written to. As such, "ctime" will list more files than "mtime" does; I would suggest using "ctime", since that will back up files that have been e.g. renamed, or have had their mode changed, so that restoring from the backup restores those changes. Using "atime" is probably a bad idea, since that will list every file that somebody *looked at* in the given amount of time; this is a bit excessive.
lml@cbnews.ATT.COM (L. Mark Larsen) (12/21/88)
In article <388@hrc.UUCP> dan@hrc.UUCP (Dan Troxel VP) writes: > >What is the difference of the find options ctime and mtime? >How will the two different options give me two differnt listings? >Or will they? >Should I use atime, to be safe, when I do incremental backups every night? >-- >Dan Troxel VP of Computer Operations @ >Handwriting Research Corporation - 2821 E. Camelback Road Suite 600 >Phoenix, AZ 85016 WK 1-602-957-8870 HM 1-602-435-1240 >UUCP : asuvax!hrc!dan The three times are stored in the inode: atime - the last time the contents of a file were accessed mtime - the last time the contents of a file were changed ctime - the last time the inode associated with a file was changed Whenever a file is read, modified or the permissions or ownership are changed, the ctime is updated. The ctime is only updated by the operating system, the other two times can be set arbitraily using touch(1). Generally, it is best to use the mtime option to find files that have really changed. L. Mark Larsen att!atlas!lml lml@atlas.att.com