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ID Category Severity Type Date Submitted Last Update
0000764 [1003.1(2008)/Issue 7] Shell and Utilities Editorial Clarification Requested 2013-10-10 13:39 2013-10-31 16:30
Reporter fbauzac View Status public  
Assigned To ajosey
Priority normal Resolution Rejected  
Status Closed  
Name Fabrice Bauzac
Organization
User Reference
Section Shell command language 2.5.2 - Parameters and Variables
Page Number 2302
Line Number 72538-72539
Interp Status ---
Final Accepted Text
Summary 0000764: Clarify the value of $0 with regards to the dot (.) command
Description Hello,

In the page
http://pubs.opengroup.org/onlinepubs/007908799/xcu/chap2.html [^]
in section "Parameters and Variables"
$0 is described as:
"(Zero.) Expands to the name of the shell or shell script. See sh for a detailed description of how this name is derived."

Does this mean that the value of $0 changes for the time of the execution of the dot (.) command?

e.g.
$ cat main
. sourced
$ cat sourced
echo "$0"

What should the command
sh main
print? "main"? "sourced"?

According to the "sh" page
http://pubs.opengroup.org/onlinepubs/007908799/xcu/sh.html [^]
"Special parameter 0 (see Special Parameters ) is set to the value of command_file. If sh is called using a synopsis form that omits command_file, special parameter 0 is set to the value of the first argument passed to sh from its parent (for example, argv[0] for a C program), which is normally a pathname used to execute the sh utility."

So, I guess it means that the dot command does not modify $0. But I think it could be clarified in the description of $0 as such:

"(Zero.) Expands to the name of the shell or shell script. See sh for a detailed description of how this name is derived. Note: files executed via the dot (.) command do not count as shell scripts."

(Sorry for my bad English. I'm not sure how to reword it better.)

Thanks!

Best regards
Fabrice
Desired Action Replace
"(Zero.) Expands to the name of the shell or shell script. See sh for a detailed description of how this name is derived."
to
"(Zero.) Expands to the name of the shell or shell script. Files executed via the dot (.) command do not count as shell scripts. See sh for a detailed description of how this name is derived."
Tags No tags attached.
Attached Files

- Relationships
related to 0000252Closedajosey dot should follow Utility Syntax Guidelines 

-  Notes
(0001876)
Don Cragun (manager)
2013-10-10 18:57

 The description of the dot special built-in utility clearly states:
The shell shall execute commands from the file in the current environment.

and the description of the Shell Execution Environment says that one of the items in the environment is:
Shell parameters that are set by variable assignment (see the set special built-in) or from
the System Interfaces volume of POSIX.1-2008 environment inherited by the shell when it
begins (see the export special built-in)

and the positional parameters are included in this item in the list.

So, $0 is not allowed to be changed to the name of the operand given to the dot command.
(0001877)
eblake (manager)
2013-10-10 19:51

 Of course, once 0000252 is incorporated, an implementation could add an extension such as '. -a name file args', similar to the common 'exec -a name' extension used to set argv[0] of an executed app.

- Issue History
Date Modified Username Field Change
2013-10-10 13:39 fbauzac New Issue
2013-10-10 13:39 fbauzac Status New => Under Review
2013-10-10 13:39 fbauzac Assigned To => ajosey
2013-10-10 13:39 fbauzac Name => Fabrice Bauzac
2013-10-10 13:39 fbauzac Section => Shell command language - Parameters and Variables
2013-10-10 13:39 fbauzac Page Number => na
2013-10-10 13:39 fbauzac Line Number => na
2013-10-10 18:57 Don Cragun Note Added: 0001876
2013-10-10 19:51 eblake Note Added: 0001877
2013-10-10 19:51 eblake Relationship added related to 0000252
2013-10-10 20:38 Don Cragun Section Shell command language - Parameters and Variables => Shell command language 2.5.2 - Parameters and Variables
2013-10-10 20:38 Don Cragun Page Number na => 2302
2013-10-10 20:38 Don Cragun Line Number na => 72538-72539
2013-10-10 20:38 Don Cragun Interp Status => ---
2013-10-31 16:30 Don Cragun Status Under Review => Closed
2013-10-31 16:30 Don Cragun Resolution Open => Rejected

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