Re: [Bug-tar] what is the point of archiving /proc "files" if you can't extract them later?

[Neal P. Murphy]

How about /proc/kcore (which really must not be restored)?

N


On Sat, 5 Nov 2016 19:39:26 -0700
Paul Eggert <address@hidden> wrote:

> 積丹尼 Dan Jacobson wrote:
> > Well the archive created sure has a lot of their content. od -c will
> > prove it to you.
> 
> No, the archive contains only metadata, not contents. For example:
> 
> $ cd /proc/self
> $ tar -cf - limits | od -c
> 0000000   l   i   m   i   t   s  \0  \0  \0  \0  \0  \0  \0  \0  \0  \0
> 0000020  \0  \0  \0  \0  \0  \0  \0  \0  \0  \0  \0  \0  \0  \0  \0  \0
> *
> 0000140  \0  \0  \0  \0   0   0   0   0   4   4   4  \0   0   0   0   1
> 0000160   7   5   0  \0   0   0   0   1   7   5   0  \0   0   0   0   0
> 0000200   0   0   0   0   0   0   0  \0   1   3   0   0   7   5   1   3
> 0000220   3   1   2  \0   0   1   1   5   7   5  \0       0  \0  \0  \0
> 0000240  \0  \0  \0  \0  \0  \0  \0  \0  \0  \0  \0  \0  \0  \0  \0  \0
> *
> 0000400  \0   u   s   t   a   r          \0   e   g   g   e   r   t  \0
> 0000420  \0  \0  \0  \0  \0  \0  \0  \0  \0  \0  \0  \0  \0  \0  \0  \0
> 0000440  \0  \0  \0  \0  \0  \0  \0  \0  \0   e   g   g   e   r   t  \0
> 0000460  \0  \0  \0  \0  \0  \0  \0  \0  \0  \0  \0  \0  \0  \0  \0  \0
> *
> 0024000
> 
> This contains metadata, which are something like this:
> 
> $ stat limits
>    File: 'limits'
>    Size: 0            Blocks: 0          IO Block: 1024   regular empty file
> Device: 4h/4d Inode: 304543      Links: 1
> Access: (0444/-r--r--r--)  Uid: ( 1000/  eggert)   Gid: ( 1000/  eggert)
> Access: 2016-11-05 19:34:50.841898208 -0700
> Modify: 2016-11-05 19:34:50.841898208 -0700
> Change: 2016-11-05 19:34:50.841898208 -0700
>   Birth: -
> 
> It does not contain the contents, which are something like this:
> 
> $ cat limits
> Limit                     Soft Limit           Hard Limit           Units
> Max cpu time              unlimited            unlimited            seconds
> Max file size             unlimited            unlimited            bytes
> Max data size             unlimited            unlimited            bytes
> Max stack size            8720000              unlimited            bytes
> Max core file size        0                    unlimited            bytes
> Max resident set          unlimited            unlimited            bytes
> Max processes             59772                59772                processes
> Max open files            1024                 65536                files
> Max locked memory         65536                65536                bytes
> Max address space         unlimited            unlimited            bytes
> Max file locks            unlimited            unlimited            locks
> Max pending signals       59772                59772                signals
> Max msgqueue size         819200               819200               bytes
> Max nice priority         0                    0
> Max realtime priority     0                    0
> Max realtime timeout      unlimited            unlimited            us
>