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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