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bug#10976: bugreport tail (GNU coreutils) 5.97
From: |
Eric Blake |
Subject: |
bug#10976: bugreport tail (GNU coreutils) 5.97 |
Date: |
Fri, 09 Mar 2012 10:56:22 -0700 |
User-agent: |
Mozilla/5.0 (X11; Linux x86_64; rv:10.0.1) Gecko/20120216 Thunderbird/10.0.1 |
tag 10976 notabug
thanks
On 03/09/2012 12:47 AM, Streit Andreas wrote:
> Hi,
>
> i just tried the following command with more than one file:
>
> tail -50 files_*.txt
> i get an error:
> tail: invalid option -- 5
> Try `tail --help' for more information.
Thanks for the report. However, this behavior is intentional. POSIX
says that you should be using -n50, and that while implementations may
support -50 as an extension, it is not a requirement. Your usage is
non-portable, and coreutils is alerting you to the fact.
Per 'info tail',
>> For compatibility `tail' also supports an obsolete usage `tail
>> -[COUNT][bcl][f] [FILE]', which is recognized only if it does not
>> conflict with the usage described above. This obsolete form uses
>> exactly one option and at most one file. In the option, COUNT is an
>> optional decimal number optionally followed by a size letter (`b', `c',
>> `l') to mean count by 512-byte blocks, bytes, or lines, optionally
>> followed by `f' which has the same meaning as `-f'.
>>
>> On older systems, the leading `-' can be replaced by `+' in the
>> obsolete option syntax with the same meaning as in counts, and obsolete
>> usage overrides normal usage when the two conflict. This obsolete
>> behavior can be enabled or disabled with the `_POSIX2_VERSION'
>> environment variable (*note Standards conformance::).
> If i try the same command with only one file it works properly:
> tail -50 files.txt
Yes, this is an example of the obsolete usage.
>
> If i try the modified command with more than one file it works properly:
> tail --lines=50 files_*.txt
Yes, this is the preferred style (simplified to -n).
Since the behavior is intentional, I'm closing this as not a bug.
--
Eric Blake address@hidden +1-919-301-3266
Libvirt virtualization library http://libvirt.org
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