Command line arguments

Command line arguments

[chesschi]

In cygwin, is it possible to pass arguments to a shell script file? I have
installed the latest cygwin with default packages. I found that argument
zero ($0) is correct. However, the number of arguments always returns zero
($#= 0) and $1, $2... are all null even though I did pass arguments.

Any idea? Thanks a lot!



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Re: Command line arguments

[Eliot Moss]

On 10/30/2012 10:20 AM, chesschi wrote:

 > In cygwin, is it possible to pass arguments to a shell script file? I have
 > installed the latest cygwin with default packages. I found that argument
 > zero ($0) is correct. However, the number of arguments always returns zero
 > ($#= 0) and $1, $2... are all null even though I did pass arguments.

It is not clear what you mean by "in cygwin".  If you run the bash shell,
for example, then it indeed makes the various arguments available as $1,
etc., and $# works as expected.

Perhaps you should give us more detail. I would suggest including:

- the script
- telling us the program from which you invoke the script (bash?), and
   exactly how you invoke it
- one or more of the command lines that do not seem to work as you expect

I can assure you that I use bash and bash scripts, with arguments and
fancy argument processing, all the time ...

Regards -- Eliot Moss

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Re: Command line arguments

[K Stahl]

I assume you are attempting to script in Bash, therefore I suggest reading:
http://tldp.org/LDP/abs/html/

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Re: Command line arguments

[Wynfield Henman]

Arguments do get passed.  So it seems you're doing something wrong.
You can't get any sensible answer without showing us exactly what you
command line look like.

On Tue, Oct 30, 2012 at 7:20 AM, chesschi <chesschi@gmail.com> wrote:
> In cygwin, is it possible to pass arguments to a shell script file? I have
> installed the latest cygwin with default packages. I found that argument
> zero ($0) is correct. However, the number of arguments always returns zero
> ($#= 0) and $1, $2... are all null even though I did pass arguments.
>
> Any idea? Thanks a lot!
>
>
>
> --
> View this message in context: http://cygwin.1069669.n5.nabble.com/Command-line-arguments-tp94081.html
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>
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Re: Command line arguments

[Brian Wilson]

If you have a script (e.g. foo.sh) and you wish to pass arguments to the 
script, your command line should look like "foo.sh arg1 arg2 arg3..."  The 
number of arguments will be correct and you will be able to access them as 
${1}, ${2}, etc.  Also, you may want to read up on the getopts command as a 
way to process command line arguments.

Sincerely,

Brian S. Wilson
============================================================================

> In cygwin, is it possible to pass arguments to a shell script file? 
> I have installed the latest cygwin with default packages. I found 
> that argument zero ($0) is correct. However, the number of arguments 
> always returns zero
> ($#= 0) and $1, $2... are all null even though I did pass arguments.


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Re: Command line arguments

[Andrew DeFaria]

On 10/31/2012 11:23 AM, Brian Wilson wrote:
> If you have a script (e.g. foo.sh) and you wish to pass arguments to the
> script, your command line should look like "foo.sh arg1 arg2 arg3..."  The
> number of arguments will be correct and you will be able to access them as
> ${1}, ${2}, etc.  Also, you may want to read up on the getopts command as a
> way to process command line arguments.
Technically, the {}'s are not needed. You can access them with $1, $2, 
etc. Most special characters sever as delimiters too so you can refer to 
them as "This the $1 parameter" or even "/path/to/$1/dir". But if you 
wanted to do something like this - "This is the ${1}parameter" or even 
"/path/to/$1.save/dir" but not "/path/to/$1save/dir" you'd need the {} 
(i.e. "/path/to/${1}save/dir" because otherwise the shell would be 
looking for "1save" as an env variable name.
-- 
Andrew DeFaria <http://defaria.com>
Fear has its use but cowardice has none. - Mohandas Gandhi


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Re: Command line arguments

[David T-G]

[-- Attachment #1: Type: text/plain, Size: 1298 bytes --]

Andrew, et al --

...and then Andrew DeFaria said...
% 
% On 10/31/2012 11:23 AM, Brian Wilson wrote:
...
% >${1}, ${2}, etc.  Also, you may want to read up on the getopts command as a
% >way to process command line arguments.
% Technically, the {}'s are not needed. You can access them with $1, $2, 
...
% "/path/to/$1.save/dir" but not "/path/to/$1save/dir" you'd need the {} 
% (i.e. "/path/to/${1}save/dir" because otherwise the shell would be 
% looking for "1save" as an env variable name.

... except that environment variables cannot begin with numbers :-)

  davidtg@madi:~ > cat /tmp/numvars.sh
  bash --version
  save=x
  echo $save
  1save=y
  echo $1save
  echo ${1save}
  davidtg@madi:~ > bash -x /tmp/numvars.sh
  + bash --version
  GNU bash, version 2.05a.0(1)-release (i386-portbld-freebsd4.6)
  Copyright 2001 Free Software Foundation, Inc.
  + save=x
  + echo x
  x
  + 1save=y
  /tmp/numvars.sh: 1save=y: command not found
  + echo save
  save
  /tmp/numvars.sh: ${1save}: bad substitution


% -- 
% Andrew DeFaria <http://defaria.com>
% Fear has its use but cowardice has none. - Mohandas Gandhi


HTH & Happy Hallowe'en

:-D
-- 
David T-G
See http://justpickone.org/davidtg/email/
See http://justpickone.org/davidtg/tofu.txt


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Re: Command line arguments

[Andrew DeFaria]

On 10/31/2012 12:40 PM, David T-G wrote:
> Andrew, et al --
>
> ...and then Andrew DeFaria said...
> %
> % On 10/31/2012 11:23 AM, Brian Wilson wrote:
> ...
> % >${1}, ${2}, etc.  Also, you may want to read up on the getopts command as a
> % >way to process command line arguments.
> % Technically, the {}'s are not needed. You can access them with $1, $2,
> ...
> % "/path/to/$1.save/dir" but not "/path/to/$1save/dir" you'd need the {}
> % (i.e. "/path/to/${1}save/dir" because otherwise the shell would be
> % looking for "1save" as an env variable name.
>
> ... except that environment variables cannot begin with numbers :-)
I was thinking that and should have tested it... Sorry if there was any 
confusion there.
>
>    davidtg@madi:~ > cat /tmp/numvars.sh
>    bash --version
>    save=x
>    echo $save
>    1save=y
>    echo $1save
>    echo ${1save}
>    davidtg@madi:~ > bash -x /tmp/numvars.sh
>    + bash --version
>    GNU bash, version 2.05a.0(1)-release (i386-portbld-freebsd4.6)
>    Copyright 2001 Free Software Foundation, Inc.
Interesting bash version there:

    $ bash --version
    GNU bash, version 4.1.10(4)-release (i686-pc-cygwin)
    Copyright (C) 2009 Free Software Foundation, Inc.
    License GPLv3+: GNU GPL version 3 or later
    <http://gnu.org/licenses/gpl.html>

    This is free software; you are free to change and redistribute it.
    There is NO WARRANTY, to the extent permitted by law.

You seem to be a bit behind...
>    + save=x
>    + echo x
>    x
>    + 1save=y
>    /tmp/numvars.sh: 1save=y: command not found
>    + echo save
>    save
>    /tmp/numvars.sh: ${1save}: bad substitution
>
>
> % --
> % Andrew DeFaria <http://defaria.com>
> % Fear has its use but cowardice has none. - Mohandas Gandhi
>
>
> HTH & Happy Hallowe'en
>
> :-D


-- 
Andrew DeFaria <http://defaria.com>
When everything's coming your way, you're in the wrong lane.


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Re: Command line arguments

[Andrew Defaria]

On 10/31/2012 12:40 PM, David T-G wrote:
> Andrew, et al --
>
> ...and then Andrew DeFaria said...
> %
> % On 10/31/2012 11:23 AM, Brian Wilson wrote:
> ...
> % >${1}, ${2}, etc.  Also, you may want to read up on the getopts command as a
> % >way to process command line arguments.
> % Technically, the {}'s are not needed. You can access them with $1, $2,
> ...
> % "/path/to/$1.save/dir" but not "/path/to/$1save/dir" you'd need the {}
> % (i.e. "/path/to/${1}save/dir" because otherwise the shell would be
> % looking for "1save" as an env variable name.
>
> ... except that environment variables cannot begin with numbers :-)
I was thinking that and should have tested it... Sorry if there was any 
confusion there.
>
>    davidtg@madi:~ > cat /tmp/numvars.sh
>    bash --version
>    save=x
>    echo $save
>    1save=y
>    echo $1save
>    echo ${1save}
>    davidtg@madi:~ > bash -x /tmp/numvars.sh
>    + bash --version
>    GNU bash, version 2.05a.0(1)-release (i386-portbld-freebsd4.6)
>    Copyright 2001 Free Software Foundation, Inc.
Interesting bash version there:

    $ bash --version
    GNU bash, version 4.1.10(4)-release (i686-pc-cygwin)
    Copyright (C) 2009 Free Software Foundation, Inc.
    License GPLv3+: GNU GPL version 3 or later
    <http://gnu.org/licenses/gpl.html>

    This is free software; you are free to change and redistribute it.
    There is NO WARRANTY, to the extent permitted by law.

You seem to be a bit behind...
>    + save=x
>    + echo x
>    x
>    + 1save=y
>    /tmp/numvars.sh: 1save=y: command not found
>    + echo save
>    save
>    /tmp/numvars.sh: ${1save}: bad substitution
>
>
> % --
> % Andrew DeFaria <http://defaria.com>
> % Fear has its use but cowardice has none. - Mohandas Gandhi
>
>
> HTH & Happy Hallowe'en
>
> :-D


-- 
Andrew DeFaria <http://defaria.com>
When everything's coming your way, you're in the wrong lane.

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Re: Command line arguments

[Brian Wilson]

> > % >${1}, ${2}, etc.  Also, you may want to read up on the getopts 
> > command as a % >way to process command line arguments. % Technically,
> > the {}'s are not needed. You can access them with $1, $2, ... % 
> > "/path/to/$1.save/dir" but not "/path/to/$1save/dir" you'd need the 
> > {} % (i.e. "/path/to/${1}save/dir" because otherwise the shell would 
> > be % looking for "1save" as an env variable name.
> 
> ... except that environment variables cannot begin with numbers :-)
>

True, but that won't keep the system from trying to interpret the string as 
a variable and erroring out on something a novice might easily write.

I got in the habbit of always using the "{}" (even if they aren't absolutely 
necessary) to avoid such issues on general principal.  It can also help keep 
things straight if you want to do something like the following line in a 
script 'VAR="${VAR}${VAR:+, }${VAR2}"' in a loop to create a comma-space 
separated string.  The first time through the loop, VAR is NULL and won't 
add anything to the string so only VAR2's value is assigned to VAR.  The 
next time through VAR is defined and will have "${VAR}, ${VAR2}" assigned 
back to VAR.  It's faster and cleaner than using an IF statement to do the 
same task.

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Re: Command line arguments

[Earnie Boyd]

On Thu, Nov 1, 2012 at 1:54 PM, Brian Wilson wrote:
>> > % >${1}, ${2}, etc.  Also, you may want to read up on the getopts
>> > command as a % >way to process command line arguments. % Technically,
>> > the {}'s are not needed. You can access them with $1, $2, ... %
>> > "/path/to/$1.save/dir" but not "/path/to/$1save/dir" you'd need the
>> > {} % (i.e. "/path/to/${1}save/dir" because otherwise the shell would
>> > be % looking for "1save" as an env variable name.
>>
>> ... except that environment variables cannot begin with numbers :-)
>>
>
> True, but that won't keep the system from trying to interpret the string as
> a variable and erroring out on something a novice might easily write.
>

Actually, I started to state this as well then I tried it.  To my
surprise ``echo $1save'' echoed the contents of $1 followed by the
string save.

> I got in the habbit of always using the "{}" (even if they aren't absolutely
> necessary) to avoid such issues on general principal.

A generally good habit to learn.  It helps to prevent the WTF moments.

-- 
Earnie
-- https://sites.google.com/site/earnieboyd

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Re: Command line arguments

[Andrew DeFaria]

On 11/1/2012 10:54 AM, Brian Wilson wrote:
> I got in the habbit of always using the "{}" (even if they aren't 
> absolutely necessary) to avoid such issues on general principal.
I don't think it's conducive to productivity to constantly type things 
that aren't needed for the simple sake of consistency - especially 
special characters which are by nature harder to type. As they say "a 
foolish consistency is the hobglobin of little minds". I add "syntactic 
sugar" only when required, much like a native English speaker doesn't 
shy away from things like contractions under a habit of always spelling 
out all words even if they aren't absolutely necessary... YMMV.
-- 
Andrew DeFaria <http://defaria.com>
I know you believe you understand what you think I said, but I'm not 
sure you realize that what you heard is not what I meant.


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Re: Command line arguments

[Earnie Boyd]

On Thu, Nov 1, 2012 at 4:48 PM, Andrew DeFaria wrote:
> On 11/1/2012 10:54 AM, Brian Wilson wrote:
>>
>> I got in the habbit of always using the "{}" (even if they aren't
>> absolutely necessary) to avoid such issues on general principal.
>
> I don't think it's conducive to productivity to constantly type things that
> aren't needed for the simple sake of consistency - especially special
> characters which are by nature harder to type. As they say "a foolish
> consistency is the hobglobin of little minds". I add "syntactic sugar" only
> when required, much like a native English speaker doesn't shy away from
> things like contractions under a habit of always spelling out all words even
> if they aren't absolutely necessary... YMMV.

YMMV when it comes time for maintenance by someone other than the code
creator.  Consistency helps reduce cost and reducing company cost
helps increase my pay check.  Taking a few seconds to use {} to
delimit all variables is priceless in the world of maintenance.  As a
native English (American) speaker, I find myself more than once
expanding contractions to make myself more clear about what I want to
convey.  Contractions for contraction sake is not always a good thing.

-- 
Earnie
-- https://sites.google.com/site/earnieboyd

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Re: Command line arguments

[Andrew DeFaria]

On 11/02/2012 05:36 AM, Earnie Boyd wrote:
> YMMV when it comes time for maintenance by someone other than the code creator.  Consistency helps reduce cost and reducing company cost helps increase my pay check.
I disagree. A [emphasis on] *foolish* consistency doesn't do anything to 
reduce cost. It's something programmers believe helps, then they spend a 
lot of time making things consistent for consistency's sake based upon 
this myth and thus adds cost not reduces it. Sprinkling syntactic sugar 
obscures the clarity of things, again, IMHO.

Don't get me wrong - some forms of consistency are good and do help 
reduce cost because readability increases. But syntactic sugar is there 
for the computer - not the human.

As for paycheck, I can assure you that mine is at an all time high and 
way above the average (like 3x).
> Taking a few seconds to use {} to delimit all variables is priceless in the world of maintenance.
No, IMHO it's wasteful to spend time doing this non-productive activity 
when it's the rare case that it is truly needed.
> As a native English (American) speaker, I find myself more than once expanding contractions to make myself more clear about what I want to convey.
And it probably ain't any clearer to anybody. If consistency in language 
was that much of a concern and you really wanted to make it such that 
you are absolutely clear then you should drop English ( 
http://defaria.com/Jokes/Plan4ImprovementOfEnglishSpelling.php and 
http://defaria.com/Jokes/CrazyLanguage.php) and pick up Lojban ( 
http://en.wikipedia.org/wiki/Lojban). Of course then you'd be talking to 
yourself pretty much.
> Contractions for contraction sake is not always a good thing.
Nobody said it was. This was an *example* - intended to convey a higher 
and deeper meaning. Think about it instead of simply taking it literally.

And with that I think we should end this, pretty much off topic 
discussion (take it to email if you'd like).
-- 
Andrew DeFaria <http://defaria.com>
One time a cop pulled me over for running a stop sign. He said "Didn't 
you see the stop sign." I said "Yeah, but I don't believe everything I 
read."


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Re: Command line arguments

[Eliot Moss]

On 11/2/2012 10:32 AM, Andrew DeFaria wrote:
> On 11/02/2012 05:36 AM, Earnie Boyd wrote:

Can we declare an end to the philosophical flames
on how to write uses of parameters in bash scripts,
please?

Maybe if we're friendly enough the OP will actually
share what the real problem was and we can offer
some specific help ...

Regards -- Eliot Moss

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Re: Command line arguments

[Christopher Faylor]

On Fri, Nov 02, 2012 at 10:54:25AM -0400, Eliot Moss wrote:
>On 11/2/2012 10:32 AM, Andrew DeFaria wrote:
>>On 11/02/2012 05:36 AM, Earnie Boyd wrote:
>
>Can we declare an end to the philosophical flames on how to write uses
>of parameters in bash scripts, please?

I know that I, of all people, shouldn't be encouraging this type of
thing but I actually found the discussion interesting.  But, you're
right, and Andrew even acknowledged that the discussion had strayed
and should be taken elsewhere.

But, if anyone wants to continue the philosophy, I'll grant a TITTL
waiver.

>Maybe if we're friendly enough the OP will actually share what the real
>problem was and we can offer some specific help ...

Or, we could even call this whole discussion closed since it seems to
have nothing to do with Cygwin and even the non-philosophical part seems
to have been beaten to death.

cgf

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