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IDProjectCategoryView StatusDate SubmittedLast Update
00012041003.1(2016/18)/Issue7+TC2Shell and Utilitiespublic2018-08-31 16:222024-06-11 09:08
Reportersalty-horse Assigned To 
PrioritynormalSeverityObjectionTypeClarification Requested
Status ClosedResolutionAccepted As Marked 
NameOri Avtalion
Organization
User Reference
Sectioned
Page Number0
Line Number0
Interp StatusApproved
Final Accepted TextSee 0001204:0004346
Summary0001204: Vague wording as to the validity of s/RE command without trailing delimiter and replacement
DescriptionThe s (Substitute) command has the following format:
  (.,.)s/RE/replacement/flags

Under the heading "Commands in ed", the specification says:

  "If the closing delimiter of an RE or of a replacement string (for example, '/' ) in a g, G, s, v, or V command would be
  the last character before a <newline>, that delimiter can be omitted, in which case the addressed line shall be written.
  For example, the following pairs of commands are equivalent:

    s/s1/s2 s/s1/s2/p
    g/s1 g/s1/p
    ?s1 ?s1?"

The wording "the closing delimiter of an RE or of a replacement string" is vague, and can be read as either referring to both the RE and replacement fields of the s command, or just the last field (as it refers to both commands with one argument, and commands with two arguments).

The "s" example is of a command that includes both the RE and replacement, without the closing delimiter.
However, there is no example such as "s/s1" or "s/s1/".
It is not specified in the text if "s/s1" is a valid commands, or how should they behave - specifically, what should be the value of the replacement string.

In contrast, the specification for the ex utility clearly allows "s/s1", and describe how it should be handled:
  (quote from the "Substitute" section)
  "The trailing delimiter can be omitted from pattern or from repl at the end of the command line. [...]
  If only repl is not specified or is empty, the pattern shall be replaced by nothing."

Of the various ed implementation I surveyed, all of them allow for "s/s1", with the replacement string being empty.
One exception is GNU ed, which in the recent release 1.14.2 has decided that "s/s1" is invalid.
See https://lists.gnu.org/archive/html/bug-ed/2017-10/msg00003.html
Desired ActionClarify whether the partial command "s/s1" is valid, and how it should be interpreted.
Tagstc3-2008

Activities

nick

2019-03-28 16:12

manager   bugnote:0004346

Last edited: 2019-03-28 16:12

 Interpretation response
------------------------
The standard states that lines "shall be written" for all of the g, G, s, v, or V commands, and conforming implementations must conform to this. However, concerns have been raised about this which are being referred to the sponsor.

Rationale:
-------------
Current implementations of ed do not behave as described in the standard.

Notes to the Editor (not part of this interpretation):
-------------------------------------------------------
 
On page 2681 line 87421 section ed, change:

If the closing delimiter of an RE or of a replacement string (for example, '/') in a g, G, s, v, or V command would be the last character before a <newline>, that delimiter can be omitted, in which case the addressed line shall be written.

to:
  

  In the following commands, if a closing delimiter would be the last character before a <newline> then that character can be omitted with the behavior shown:
      

          
  • For the g and v commands the addressed line(s) shall be written as if a closing delimiter followed by a p were appended to the command.

    •       
  • For the G and V commands no additional action shall be taken.

    •       
  • For the s command, only the closing delimiter of the replacement can be omitted, in which case the result of the substitution shall be written as if the p flag were appended.

    •       
  • For the null command, the addressed line(s) shall be written as if the closing delimiter were appended.

    •       

agadmin

2019-10-07 15:17

administrator   bugnote:0004610

Interpretation proposed: 7 October 2019

agadmin

2019-11-11 12:21

administrator   bugnote:0004654

Interpretation Approved: 11 Nov 2019

Issue History

Date Modified Username Field Change
2018-08-31 16:22 salty-horse New Issue
2018-08-31 16:22 salty-horse Name => Ori Avtalion
2018-08-31 16:22 salty-horse Section => ed
2018-08-31 16:22 salty-horse Page Number => 0
2018-08-31 16:22 salty-horse Line Number => 0
2019-03-28 16:12 nick Note Added: 0004346
2019-03-28 16:12 nick Note Edited: 0004346
2019-03-28 16:13 nick Interp Status => Pending
2019-03-28 16:13 nick Final Accepted Text => See 0001204:0004346
2019-03-28 16:13 nick Status New => Interpretation Required
2019-03-28 16:13 nick Resolution Open => Accepted As Marked
2019-03-28 16:14 nick Tag Attached: tc3-2008
2019-10-07 15:17 agadmin Interp Status Pending => Proposed
2019-10-07 15:17 agadmin Note Added: 0004610
2019-11-11 12:21 agadmin Interp Status Proposed => Approved
2019-11-11 12:21 agadmin Note Added: 0004654
2019-12-04 11:37 geoffclare Status Interpretation Required => Applied
2024-06-11 09:08 agadmin Status Applied => Closed