View Issue Details
| ID | Project | Category | View Status | Date Submitted | Last Update |
|---|---|---|---|---|---|
| 0000224 | 1003.1(2008)/Issue 7 | Shell and Utilities | public | 2010-02-25 17:29 | 2013-04-16 13:06 |
| Reporter | geoffclare | Assigned To | ajosey | ||
| Priority | normal | Severity | Objection | Type | Error |
| Status | Closed | Resolution | Accepted As Marked | ||
| Name | Geoff Clare | ||||
| Organization | The Open Group | ||||
| User Reference | |||||
| Section | awk | ||||
| Page Number | 2430 | ||||
| Line Number | 77098 | ||||
| Interp Status | Approved | ||||
| Final Accepted Text | 0000224:0000396 | ||||
| Summary | 0000224: awk -F and FS | ||||
| Description | There are a couple of problems with the description of the awk -F option: -F ERE Define the input field separator to be the extended regular expression ERE, before any input is read 1. By a strict reading, the ERE option-argument is used directly as an extended regular expression, but in practice the option-argument is handled as if it were a string literal to be assigned to the FS variable. This makes a difference to the treatment of backslash characters: $ awk -F '\\\\' 'BEGIN { print FS }' \\ Here the ERE used as input field separator is \\ not \\\\. It is the same as for: $ awk 'BEGIN { FS="\\\\"; print FS }' \\ 2. The input field separator (and consequently the FS variable) should be set before execution of any BEGIN actions, not just before any input is read, so that applications can use FS within BEGIN actions. E.g.: BEGIN { OFS=FS } | ||||
| Desired Action | Change -F ERE Define the input field separator to be the extended regular expression ERE, before any input is read; see [xref to Regular Expressions]. to -F sepstring Define the input field separator as if by the assignment FS = "sepstring" before execution of the actions associated with any BEGIN patterns, or before any input is read if there are no BEGIN patterns; see the description of the FS built-in variable, and how it is used, in the EXTENDED DESCRIPTION section. In the SYNOPSIS change -F ERE on lines 77077 and 77078 to -F sepstring On line 77091 change -F ERE to the -F sepstring option At line 77514 change An extended regular expression can be used to separate fields by using the -F ERE option or by assigning a string containing the expression to the built-in variable FS. to An extended regular expression can be used to separate fields by assigning a string containing the expression to the built-in variable FS, either directly or as a consequence of using the -F sepstring option. | ||||
| Tags | tc1-2008 | ||||
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I suppose we could describe -F <whatever> as being the same as -v FS=<whatever> |
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Stephane's suggestion would be a neater way to specify the behaviour. However, the two ways are not quite the same and on further investigation, it turns out that some implementations behave one way and some the other. awk -F A -v FS=B 'BEGIN { print FS }' prints B, as per Stephane's suggestion, in some versions of awk (e.g. Solaris, GNU) but prints A, as per my original proposal, in others (e.g. HP-UX, Unixware). Here is an updated proposal which reflects this finding... Change -F ERE Define the input field separator to be the extended regular expression ERE, before any input is read; see [xref to Regular Expressions]. to -F sepstring Define the input field separator. This option shall be equivalent to -v FS=sepstring except that if -F sepstring and -v FS=sepstring are both used, it is unspecified whether the FS assignment resulting from -F sepstring is processed in command line order or is processed after the last -v FS=sepstring. See the description of the FS built-in variable, and how it is used, in the EXTENDED DESCRIPTION section. In the SYNOPSIS change -F ERE on lines 77077 and 77078 to -F sepstring On line 77091 change -F ERE to the -F sepstring option At line 77514 change An extended regular expression can be used to separate fields by using the -F ERE option or by assigning a string containing the expression to the built-in variable FS. to An extended regular expression can be used to separate fields by assigning a string containing the expression to the built-in variable FS, either directly or as a consequence of using the -F sepstring option. |
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Interpretation response ------------------------ The standard states the requirements for awk -F, and conforming implementations must conform to this. However, concerns have been raised about this which are being referred to the sponsor. Notes to the Editor (not part of this interpretation): ------------------------------------------------------- Change -F ERE Define the input field separator to be the extended regular expression ERE, before any input is read; see [xref to Regular Expressions]. to -F sepstring Define the input field separator. This option shall be equivalent to -v FS=sepstring except that if -F sepstring and -v FS=sepstring are both used, it is unspecified whether the FS assignment resulting from -F sepstring is processed in command line order or is processed after the last -v FS=sepstring. See the description of the FS built-in variable, and how it is used, in the EXTENDED DESCRIPTION section. In the SYNOPSIS change -F ERE on lines 77077 and 77078 to -F sepstring On line 77091 change -F ERE to the -F sepstring option At line 77514 change An extended regular expression can be used to separate fields by using the -F ERE option or by assigning a string containing the expression to the built-in variable FS. to An extended regular expression can be used to separate fields by assigning a string containing the expression to the built-in variable FS, either directly or as a consequence of using the -F sepstring option. |
| Date Modified | Username | Field | Change |
|---|---|---|---|
| 2010-02-25 17:29 | geoffclare | New Issue | |
| 2010-02-25 17:29 | geoffclare | Status | New => Under Review |
| 2010-02-25 17:29 | geoffclare | Assigned To | => ajosey |
| 2010-02-25 17:29 | geoffclare | Name | => Geoff Clare |
| 2010-02-25 17:29 | geoffclare | Organization | => The Open Group |
| 2010-02-25 17:29 | geoffclare | Section | => awk |
| 2010-02-25 17:29 | geoffclare | Page Number | => 2430 |
| 2010-02-25 17:29 | geoffclare | Line Number | => 77098 |
| 2010-02-25 17:29 | geoffclare | Interp Status | => --- |
| 2010-02-25 19:22 | stephane | Note Added: 0000391 | |
| 2010-02-26 09:43 | geoffclare | Note Added: 0000392 | |
| 2010-03-04 17:12 | geoffclare | Interp Status | --- => Pending |
| 2010-03-04 17:12 | geoffclare | Note Added: 0000396 | |
| 2010-03-04 17:12 | geoffclare | Status | Under Review => Interpretation Required |
| 2010-03-04 17:12 | geoffclare | Resolution | Open => Accepted As Marked |
| 2010-03-04 17:12 | geoffclare | Description Updated | |
| 2010-03-04 17:13 | geoffclare | Final Accepted Text | => 0000224:0000396 |
| 2010-04-16 10:14 | ajosey | Interp Status | Pending => Proposed |
| 2010-05-28 14:04 | ajosey | Interp Status | Proposed => Approved |
| 2010-09-24 11:16 | geoffclare | Tag Attached: tc1-2008 | |
| 2013-04-16 13:06 | ajosey | Status | Interpretation Required => Closed |
