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| ID | Category | Severity | Type | Date Submitted | Last Update | ||
| 0000975 | [1003.1(2008)/Issue 7] Shell and Utilities | Editorial | Clarification Requested | 2015-08-11 15:25 | 2016-06-02 15:16 | ||
| Reporter | joerg | View Status | public | ||||
| Assigned To | ajosey | ||||||
| Priority | normal | Resolution | Withdrawn | ||||
| Status | Closed | ||||||
| Name | Jörg Schilling | ||||||
| Organization | |||||||
| User Reference | |||||||
| Section | fc | ||||||
| Page Number | 2745-2759 | ||||||
| Line Number | 89811-90031 | ||||||
| Interp Status | --- | ||||||
| Final Accepted Text | |||||||
| Summary | 0000975: fc prevents better history implementations, so remove it or make it optional | ||||||
| Description |
The fc command is based on the history mechanism as seen in csh and based on a command serial number that does not change as long as a command is in the history. There however exist better mechanisms that implement the history as a lru list where each called command is in the history only once and if the same command is called again, it is moved from it's previous place to the last recently used location. This method is easier to understand than the cah/ksh method. Implementor should not be forced to implement an inferior concept just because POSIX defines fc to be mandatory. Note that the lru history mechanism was developed in 1982 and a fully working implementation exists since 1984. This history mechanism was added to the Bourne Shell in 2006. |
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| Desired Action | Mark the fc command optional or better completely remove it. | ||||||
| Tags | No tags attached. | ||||||
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Notes |
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(0003235) shware_systems (reporter) 2016-05-27 13:39 |
As discussed in the 20160526 phone call, there are current usage cases where the full history is necessary, duplicate entries included in temporal order, and so is still desirable. Maintaining some method of scriptable bulk access to the history log was also seen as desirable enough to be non-optional, as well, so the Desired Action was nominally rejected. The general consensus was the intent of the standard was not to preclude additional ways of implementing the generic 'history' concept that some may consider subjectively better, however, so this bug is being left open as a TODO item for an implementation of the fc utility that includes a means that the user can select which method to use from implementation-defined alternatives, with the current specification being the default behavior. This might include the above lossy LRU method or a workalike from a usage perspective. Various ways this might be accomplished were proposed, if not in depth. Collateral impacts on other utilities was also touched upon, but time expired. |
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(0003240) nick (manager) 2016-06-02 15:11 |
Withdrawn by submitter; a new issue will be created if necessary to add additional functionality. |
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Issue History |
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| Date Modified | Username | Field | Change |
| 2015-08-11 15:25 | joerg | New Issue | |
| 2015-08-11 15:25 | joerg | Status | New => Under Review |
| 2015-08-11 15:25 | joerg | Assigned To | => ajosey |
| 2015-08-11 15:25 | joerg | Name | => Jörg Schilling |
| 2015-08-11 15:25 | joerg | Section | => fc |
| 2015-08-11 15:25 | joerg | Page Number | => 2745-2759 |
| 2015-08-11 15:25 | joerg | Line Number | => 89811-90031 |
| 2016-05-27 13:39 | shware_systems | Note Added: 0003235 | |
| 2016-06-02 15:10 | nick | Interp Status | => --- |
| 2016-06-02 15:10 | nick | Resolution | Open => Withdrawn |
| 2016-06-02 15:11 | nick | Note Added: 0003240 | |
| 2016-06-02 15:16 | nick | Status | Under Review => Closed |
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