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Re: understanding C issues in geany install

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On 02/01/2018 12:39 PM, James R. Kuyper wrote:
> On 02/01/2018 02:55 PM, fred flintstone wrote:
> ...
>> Q1) Does contemporary standard C have any defined relationship to the
>> shell, from the point of view of C?
> 
> "#include <stdlib.h>
> int system(const char *string);
> 
> If string is a null pointer, the system function determines whether the 
> host environment has a command processor. If string is not a null 
> pointer, the system function passes the string pointed to by string to 
> that command processor to be executed in a manner which the 
> implementation shall document; this might then cause the program calling 
> system to behave in a non-conforming manner or to terminate.
> 
> Returns
> If the argument is a null pointer, the system function returns nonzero 
> only if a command processor is available. If the argument is not a null 
> pointer, and the system function does return, it returns an 
> implementation-defined value." (7.22.4.8)
> 
> That is the only defined relationship between them.
> 
> Given the implementation-dependence of the behavior of system(), it's 
> close to impossible to make any portable use of that function.

ok
> 
>> Running ./configure  ...
>> checking for a BSD-compatible install... /usr/bin/install -c
>> checking whether build environment is sane... yes
>> checking for a thread-safe mkdir -p... /bin/mkdir -p
>>
>> Q2) What does -c entail in the above?
> 
> That's a question about the install command; on a Unix-like system, if 
> the man pages have been correctly installed, you should be able to get 
> the answer by typing:
> 
>      man install
> 
> "man" in the name for the online user manual program. On the system I'm 
> using right now, the man page indicates "install" ignores the -c option. 
> This kind of thing happens if something that used to be optional has 
> become standard, so there's no longer any need to have an option to make 
> it happen. The option is still allowed, so people don't have to rewrite 
> their build scripts, but it doesn't change anything.

It didn't occur to me that I could "man install," where I find this:

    -c     (ignored)

> 
>> Q3) When I script, I write
>> mkdir -p boulder
>> , without really knowing why. Is there a place I can look at the C
>> source of mkdir on my machine to ascertain why?
> 
> Possibly, but typing
> 
>      man mkdir
> 
> is a much simpler way to the get the answer:
> 
> "       -p, --parents
>                no error if existing, make parent directories as needed"
> 
> What this means is that instead of typing:
>      mkdir parent
>      mkdir parent/child
> 
> you can type
>      mkdir -p parent/child
> 
> And it will first create the parent directory, if necessary, and then 
> parent/child. Without the -p option, it would look for a parent 
> directory to place child in, not find it, and generate an error message. 
> It is therefore never necessary to use -p unless there's at least one 
> '/' in the pathname for the directory you want to create.

Gotcha. I'd never quite figured this out.
> 
>> $ lsb_release -a
>> No LSB modules are available.
>> Distributor ID:    Ubuntu
>> Description:    Ubuntu 16.04.3 LTS
>> Release:    16.04
>> Codename:    xenial
>> $
>>
>> checking for gcc... gcc
>> checking whether the C compiler works... yes
>> checking for C compiler default output file name... a.out
>> checking for suffix of executables...
>> checking whether we are cross compiling... no
>> checking for suffix of object files... o
>> checking whether we are using the GNU C compiler... yes
>> checking whether gcc accepts -g... yes
>> checking for gcc option to accept ISO C89... none needed
>> checking whether gcc understands -c and -o together... yes
>> checking dependency style of gcc... gcc3
>> checking how to run the C preprocessor... gcc -E
>>
>> Nothing crazy looking here. Do I gather correctly that g is an alias for
>> gcc?
> 
> The only isolated g in the above output is on the following line:
>  > checking whether gcc accepts -g... yes
> 
> That g is NOT an alias for gcc. It is part of -g, which is an option 
> that gcc might or might not accept. You can get information about gcc by 
>   typing:
>      man gcc
> 
> If you type "/ -g ", man will search for the string " -g ". Hit "n" as 
> needed to continue on to the next match. On my system, I had to hit "n" 
> 5 times to get to the correct description, which says:
> 
> "-g Produce debugging information in the operating system's native
>             format (stabs, COFF, XCOFF, or DWARF 2).  GDB can work with
>             this debugging information."
> 
>> Also, curious how C 89 and 99 were made to gyve:
>> checking for gcc option to accept ISO C99... none needed
>>
>> checking if gcc static flag -static works... yes
>> checking if gcc supports -c -o file.o... yes
>> checking if gcc supports -c -o file.o... (cached) yes
>>
>> Again, cloudy about -c in this context.
> 
> In this case, -c is a option on the gcc command. from "man gcc":
> 
> "-c Compile or assemble the source files, but do not link.  The linking
>             stage simply is not done.  The ultimate output is in the form
>             of an object file for each source file."

So -c has a different context here.
> 
>> Finally, I have one Big Question:
>>
>> Does the C Programming Language, as defined by C99, define anything
>> about the shells that surround it? It's alright if the answer is no; I
>> just want to know what it is.
> 
> No.
> 
>>   From C's point of view, what is bash?
> 
> Nothing. Such matters are outside the scope of the C standard.
> 
>> ... Does bash have a standard it
>> adheres to? Is that POSIX?
> 
> See <https://en.wikipedia.org/wiki/Bash_(Unix_shell)>.
> 
> bash is a freeware replacement for the Bourne shell, sh. It's widely 
> available on Linux and macOS platforms, and there's a Windows 10 
> compatible version as well. sh is defined by a POSIX standard. Executing 
> "bash -posix" makes it conform very closely to the POSIX requirements 
> for sh.

Alright, these were the answers I was looking for. It's very helpful for 
me to sort out which standard applies. This script:

https://github.com/TBlazer66/island/blob/master/1.repos.sh

aims to install geany on debian systems. I can get scripts to save now, 
but still cannot get them to conform to an indenting scheme, so these 
scripts are still super jagged.

Thanks all for comments,
-- 
fred flintstone

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Thread

understanding C issues in geany install fred flintstone <fred@server.invalid> - 2018-02-01 11:55 -0800
  Re: understanding C issues in geany install Malcolm McLean <malcolm.arthur.mclean@gmail.com> - 2018-02-01 12:04 -0800
  Re: understanding C issues in geany install Keith Thompson <kst-u@mib.org> - 2018-02-01 12:19 -0800
    Re: understanding C issues in geany install Jorgen Grahn <grahn+nntp@snipabacken.se> - 2018-02-04 19:24 +0000
      Re: understanding C issues in geany install David Kleinecke <dkleinecke@gmail.com> - 2018-02-04 16:02 -0800
  Re: understanding C issues in geany install "James R. Kuyper" <jameskuyper@verizon.net> - 2018-02-01 15:39 -0500
    Re: understanding C issues in geany install fred flintstone <fred@server.invalid> - 2018-02-07 07:44 -0800
  Re: understanding C issues in geany install Joe Pfeiffer <pfeiffer@cs.nmsu.edu> - 2018-02-01 16:08 -0700
  Re: understanding C issues in geany install gordonb.669da@burditt.org (Gordon Burditt) - 2018-02-05 20:56 -0600
  Re: understanding C issues in geany install John Bode <jfbode1029@gmail.com> - 2018-02-06 09:26 -0800
    Re: understanding C issues in geany install Keith Thompson <kst-u@mib.org> - 2018-02-06 12:36 -0800
    Re: understanding C issues in geany install "James R. Kuyper" <jameskuyper@verizon.net> - 2018-02-06 15:49 -0500
      Re: understanding C issues in geany install scott@slp53.sl.home (Scott Lurndal) - 2018-02-06 21:37 +0000

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