Patent US6615224B1 successfully refreshed from Google Patents.
US6615224B1
Expired / Lapsed
US
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High-performance UNIX file undelete
Assignee: Individual
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Filing: 1999-02-23
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Granted: 2003-09-02
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Expires: 2019-02-23
Abstract
Abstract A method for deleting files on a UNIX file system, so that they may subsequently be undeleted, without any possibility of loss or damage. A file deleted with the “rm” command, or targeted by the “cp” or “mv” commands, is deleted simply by marking its directory record “deleted”, while its inode and data blocks are not freed. The “ls” command is adjusted so as not to display files whose directory records are marked as deleted. A indexed system of deleted-file records of such deleted files is maintained by the UNIX kernel, such that a record for each deleted file contains a pointer to the file's inode, a pointer to the file's directory inode, and the file's deletion time. A deleted file may be undeleted simply by calling an “unrm <file>” command, which uses a kernel system call to undo “deleted” mark in the file's directory record. This procedure restores the file completely, because its inode and data blocks were never freed. The “ls” command again will display the file. The indexed system of deleted-file records, created over time as files are deleted from the UNIX file system, is a necessary tool used by the kernel to efficiently remove the oldest deleted files from the system automatically, without excess system overhead, and without cumbersome system maintenance procedures required from the system administrator.
Inventors
- 👤 Lewis B. Davis
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-09 10:54
CPC Classifications
G; G06; G06F; G06F16/00; G06F16/10; Y; Y10; Y10S; Y10S707/00; Y10S707/99951; Y10S707/99952; Y10S707/99953
Claims Analysis
Total Claims: 8
Claim 1
Independent Claim
178 words
A method for deleting a plurality of files on a UNIX filesystem comprising the steps of: a) setting a flag which marks the directory record for a first file as deleted, such that the “ls” function for the first file recognizes said flag and does not display said first file; b) storing the inode pointer of said first file, the directory pointer of the directory containing said first file, and the deletion time of said first file in a record on a recording medium which, if it is a volatile recording medium such as RAM memory, may be synchronized to a durable recording medium when the computer system is shut down; c) repeat steps (a) and (b) for a second file of said plurality of files, appending said record for the second file in a sequential manner to said record for the first file; d) repeat steps (a) and (b) for subsequent files of said plurality of files, each time appending said record for said subsequent file in a sequential manner to said record for the previous file.
Claim 2
Independent Claim
178 words
A method for deleting a plurality of files on a UNIX filesystem comprising the steps of: a) setting a flag which marks the directory record for a first file as deleted, such that the “ls” function for the first file recognizes said flag and does not display said first file; b) storing the inode pointer of said first file, the directory pointer of the directory containing said first file, and the deletion time of said first file in a record on a recording medium which, if it is a volatile recording medium such as RAM memory, may be synchronized to a durable recording medium when the computer system is shut down; c) repeat steps (a) and (b) for a second file of said plurality of files, appending said record for the second file in a sequential manner to said record for the first file; d) repeat steps (a) and (b) for subsequent files of said plurality of files, each time appending said record for said subsequent file in a sequential manner to said record for the previous file.
Claim 3
Independent Claim
101 words
The method of claim ( 1 ) further comprises a method for restoring a file from said plurality of deleted files comprised of the following steps: a) unsetting the flag which marked the directory record for said file as deleted, such that the “ls” function no longer reads said flag in the directory record for said file, and thus displays said file; b) setting a flag which marks said record as undeleted, that is the said record which contains the inode pointer of said file, the directory pointer of the directory containing said file, and the deletion time of said file.
Claim 4
Independent Claim
167 words
The method of claim ( 1 ) further comprises a method for completely removing some of the files in said plurality of deleted files comprised of the following steps: a) choosing the oldest record which is not flagged inactive from among said sequential system of records corresponding to the said plurality of deleted files; b) using the pointer to the directory and pointer to the inode contained in said record to remove the directory record for the deleted file in the directory which corresponds to said inode pointer; c) using the pointer to the inode contained in said record to completely remove the data blocks associated with the inode and to completely remove the inode itself from the UNIX file system; d) flag said record as inactive; e) repeat steps (a)-(d) for successive oldest records, which are not flagged inactive, in said sequential system of records corresponding to the said plurality of deleted files, until a minimum size threshold for the sequential system of records is met.
Claim 5
Independent Claim
139 words
A method for deleting a plurality of files on a UNIX filesystem comprising the steps of: a) marking the directory record for a first file as deleted, such that the “Is” function for the first file recognizes said marked directory record and does not display said first file; b) storing the inode pointer or index of said first file, the inode pointer or index of the directory containing said first file, and the deletion time of said first file in a deleted-file record which is indexed according to said deletion time and stored on a recording medium which, if it is a volatile recording medium such as RAM memory, may be synchronized to a durable recording medium when the computer system is shut down; c) repeat steps (a) and (b) for all subsequent files of said plurality of files.
Claim 6
Independent Claim
139 words
A method for deleting a plurality of files on a UNIX filesystem comprising the steps of: a) marking the directory record for a first file as deleted, such that the “Is” function for the first file recognizes said marked directory record and does not display said first file; b) storing the inode pointer or index of said first file, the inode pointer or index of the directory containing said first file, and the deletion time of said first file in a deleted-file record which is indexed according to said deletion time and stored on a recording medium which, if it is a volatile recording medium such as RAM memory, may be synchronized to a durable recording medium when the computer system is shut down; c) repeat steps (a) and (b) for all subsequent files of said plurality of files.
Claim 7
Independent Claim
100 words
The method of claim ( 4 ) further comprises a method for restoring a file from said plurality of deleted files comprised of the following steps: a) removing the mark on the directory record for said file, such that the “Is” function no longer recognizes said mark for said directory record for said file, and thus displays said file; b) using a means to mark said file's deleted-file record as undeleted, that is the said record which contains the inode pointer of said file, the directory pointer of the directory containing said file, and the deletion time of said file.
Claim 8
Independent Claim
202 words
The method of claim ( 4 ) further comprises a method for completely removing some of the files in said plurality of deleted files comprised of the following steps: a) using the deleted-file index to choose the oldest deleted-file record which is not marked undeleted or unactive from among said indexed system of deleted-file records corresponding to the said plurality of deleted files; b) using the pointer to or index of the inode of said file's directory and pointer to or index of the inode of said file contained in said deleted-file record to remove from the director the directory record for said deleted file; c) using the pointer to or index of the inode of said file contained in said deleted-file record to completely remove the data blocks associated with said file and to completely remove the inode itself from the UNIX file system; d) using a means to mark said deleted-file record of said file as inactive; e) repeat steps (a)-(d) for successive oldest records, which are not marked undeleted or inactive, in said indexed system of deleted-file records corresponding to the said plurality of deleted files, until a pre-determined-determined threshold size for the system of deleted-file records is met.
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USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 2006-09-01 | 2007-03-03 | 2007-09-02 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 2010-09-01 | 2011-03-03 | 2011-09-02 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 2014-09-01 | 2015-03-03 | 2015-09-02 | $7700.00 | Window Closed / Lapsed |