Delete a specific type of files when they exist.

Delete a specific type of files when they exist.

[Hongyi Zhao]

Hi all,

I want to delete the all of the cache-2 files under a directory, so I
use the following line to do this:

if [ -f *.cache-2 ] rm *.cache-2

But it seems that this -f parameter in the _if_ command will not work
with wildcard, i.e., the  _[ -f *.cache-2 ]_ isn't a valid arg.  Any
hints on this issue? 

-- 
.: Hongyi Zhao [ hongyi.zhao AT gmail.com ] Free as in Freedom :.


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Re: Delete a specific type of files when they exist.

[Yaakov (Cygwin/X)]

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Hongyi Zhao wrote:
> I want to delete the all of the cache-2 files under a directory, so I
> use the following line to do this:
> 
> if [ -f *.cache-2 ] rm *.cache-2
> 
> But it seems that this -f parameter in the _if_ command will not work
> with wildcard, i.e., the  _[ -f *.cache-2 ]_ isn't a valid arg.  Any
> hints on this issue? 

find /path/to/directory -name '*.cache-2' -delete


Yaakov
Cygwin/X
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Re: Delete a specific type of files when they exist.

[Hongyi Zhao]

On Thu, 08 Jan 2009 22:01:26 -0600, "Yaakov (Cygwin/X)"
<yselkowitz@users.sourceforge.net> wrote:

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>
>Hongyi Zhao wrote:
>> I want to delete the all of the cache-2 files under a directory, so I
>> use the following line to do this:
>> 
>> if [ -f *.cache-2 ] rm *.cache-2
>> 
>> But it seems that this -f parameter in the _if_ command will not work
>> with wildcard, i.e., the  _[ -f *.cache-2 ]_ isn't a valid arg.  Any
>> hints on this issue? 
>
>find /path/to/directory -name '*.cache-2' -delete

Good, thanks, I've got it.

-- 
.: Hongyi Zhao [ hongyi.zhao AT gmail.com ] Free as in Freedom :.


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Re: Delete a specific type of files when they exist.

[Christopher Faylor]

On Fri, Jan 09, 2009 at 11:55:46AM +0800, Hongyi Zhao wrote:
>Hi all,
>
>I want to delete the all of the cache-2 files under a directory, so I
>use the following line to do this:
>
>if [ -f *.cache-2 ] rm *.cache-2
>
>But it seems that this -f parameter in the _if_ command will not work
>with wildcard, i.e., the  _[ -f *.cache-2 ]_ isn't a valid arg.  Any
>hints on this issue? 

Why not just

  rm -f *.cache-2

?

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Re: Delete a specific type of files when they exist.

[Hongyi Zhao]

On Fri, 9 Jan 2009 00:42:21 -0500, Christopher Faylor
<cgf-use-the-mailinglist-please@cygwin.com> wrote:

>On Fri, Jan 09, 2009 at 11:55:46AM +0800, Hongyi Zhao wrote:
>>Hi all,
>>
>>I want to delete the all of the cache-2 files under a directory, so I
>>use the following line to do this:
>>
>>if [ -f *.cache-2 ] rm *.cache-2
>>
>>But it seems that this -f parameter in the _if_ command will not work
>>with wildcard, i.e., the  _[ -f *.cache-2 ]_ isn't a valid arg.  Any
>>hints on this issue? 
>
>Why not just
>
>  rm -f *.cache-2

A good idea.  Thanks.

-- 
.: Hongyi Zhao [ hongyi.zhao AT gmail.com ] Free as in Freedom :.


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Re: Delete a specific type of files when they exist.

[Eric Blake]

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According to Hongyi Zhao on 1/8/2009 8:55 PM:
> if [ -f *.cache-2 ] rm *.cache-2
> 
> But it seems that this -f parameter in the _if_ command will not work
> with wildcard, i.e., the  _[ -f *.cache-2 ]_ isn't a valid arg.  Any
> hints on this issue? 

Not cygwin specific.  Your problem is that using a glob can expand to more
than one argument, whereas "[ -f ... ]" expects exactly one argument in
place of ...; using echo will show you where you went wrong:

echo [ -f *.cache-2 ]

- --
Don't work too hard, make some time for fun as well!

Eric Blake             ebb9@byu.net
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Re: Delete a specific type of files when they exist.

[Hongyi Zhao]

On Fri, 09 Jan 2009 06:12:27 -0700, Eric Blake <ebb9@byu.net> wrote:

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>According to Hongyi Zhao on 1/8/2009 8:55 PM:
>> if [ -f *.cache-2 ] rm *.cache-2
>> 
>> But it seems that this -f parameter in the _if_ command will not work
>> with wildcard, i.e., the  _[ -f *.cache-2 ]_ isn't a valid arg.  Any
>> hints on this issue? 
>
>Not cygwin specific.  Your problem is that using a glob can expand to more
>than one argument, whereas "[ -f ... ]" expects exactly one argument in
>place of ...;

Thanks for your analyse.

> using echo will show you where you went wrong:
>
>echo [ -f *.cache-2 ]

But I cann't figure this out, see the following results on my box:

$ echo [ -f *.cache-2 ]
[ -f *.cache-2 ]

I cann't see any differences between your code and the following one:

$ echo something and something
something and something

Could you please give me some more hints?

Regards,

-- 
.: Hongyi Zhao [ hongyi.zhao AT gmail.com ] Free as in Freedom :.


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Re: Delete a specific type of files when they exist.

[Eric Blake]

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According to Hongyi Zhao on 1/9/2009 6:38 AM:
> But I cann't figure this out, see the following results on my box:
> 
> $ echo [ -f *.cache-2 ]
> [ -f *.cache-2 ]

That means there aren't any *.cache-2 files in your directory.  Next, try
this:

$ touch a.cache-2 b.cache-2
$ echo [ -f *.cache-2 ]
[ -f a.cache-2 b.cache-2 ]

See how you just gave 2 arguments (instead of the expected 1) to [ -f?

- --
Don't work too hard, make some time for fun as well!

Eric Blake             ebb9@byu.net
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Re: Delete a specific type of files when they exist.

[Hongyi Zhao]

On Fri, 09 Jan 2009 07:36:26 -0700, Eric Blake <ebb9@byu.net> wrote:

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>According to Hongyi Zhao on 1/9/2009 6:38 AM:
>> But I cann't figure this out, see the following results on my box:
>> 
>> $ echo [ -f *.cache-2 ]
>> [ -f *.cache-2 ]
>
>That means there aren't any *.cache-2 files in your directory.  Next, try
>this:
>
>$ touch a.cache-2 b.cache-2
>$ echo [ -f *.cache-2 ]
>[ -f a.cache-2 b.cache-2 ]

In your example, considering that the a.cache-2 and b.cache-2 have
been created by touch command, both the [ -f a.cache-2] and [ -f
b.cache-2 ] should have the value: true.  My issue is: how can I grab
this value, say, by using echo command?

Regards,

-- 
.: Hongyi Zhao [ hongyi.zhao AT gmail.com ] Free as in Freedom :.


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Re: Delete a specific type of files when they exist.

[Eric Blake]

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According to Hongyi Zhao on 1/10/2009 3:05 AM:
>> $ touch a.cache-2 b.cache-2
>> $ echo [ -f *.cache-2 ]
>> [ -f a.cache-2 b.cache-2 ]
> 
> In your example, considering that the a.cache-2 and b.cache-2 have
> been created by touch command, both the [ -f a.cache-2] and [ -f
> b.cache-2 ] should have the value: true.  My issue is: how can I grab
> this value, say, by using echo command?

Your question is not cygwin specific; I repeat the advice you have been
given to seek out a more generic introduction or online forum that
discusses basic shell programming constructs, rather than using this list.

That said, there are multiple ways to determine if you have one or more
file matching a given pattern.  Among others, this (bash-specific) way
avoids forking, by using nullglob to avoid confusion when a glob has no
matches, and by using printf -v to assign a variable without a command
substitution:

$ restore=
$ shopt -q nullglob || restore='shopt -u nullglob'
$ shopt -s nullglob
$ printf -v exist %s *.cache-2
$ if [ -n "$exist" ] ; then
>   echo at least one file exists with .cache-2 extension
> else
>   echo no .cache-2 exist
> fi
$ eval $restore

More portable (but at the cost some forks) is this:

$ if [ "`echo *.cache-2`" != "*.cache-2" ] || [ -f "*.cache-2" ] ; then
>   echo at least one file exists with .cache-2 extension
> else
>   echo no .cache-2 exist
> fi

which takes care of the (admittedly rare) case of having a file literally
named *.cache-2.

- --
Don't work too hard, make some time for fun as well!

Eric Blake             ebb9@byu.net
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