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CAPSH(1)			 User Commands			      CAPSH(1)

       capsh - capability shell wrapper

       capsh [OPTION]...

       Linux  capability  support and use can be explored and constrained with
       this tool. This tool provides a handy  wrapper  for  certain  types  of
       capability  testing  and	 environment  creation.	 It also provides some
       debugging features useful for summarizing capability state.

       The tool takes a number of optional arguments, acting on	 them  in  the
       order they are provided. They are as follows:

       --print		     Display prevailing capability and related state.

       -- [args]	     Execute /bin/bash with trailing arguments.

       ==		     Execute  capsh  again  with  remaining arguments.
			     Useful for testing exec() behavior.

       --caps=cap-set	     Set the prevailing process capabilities to	 those
			     specified	by  cap-set.  Where cap-set is a text-
			     representation  of	 capability   state   as   per

       --drop=cap-list	     Remove  the listed capabilities from the prevail-
			     ing bounding set. The  capabilites	 are  a	 comma
			     separated	list  of capabilities as recognized by
			     the cap_from_name(3) function. Use of  this  fea-
			     ture requires that the capsh program is operating
			     with CAP_SETPCAP in its effective set.

       --inh=cap-list	     Set the inheritable set of capabilities  for  the
			     current  process  to  equal those provided in the
			     comma separated list. For this action to succeed,
			     the  prevailing  process should already have each
			     of these capabilities in the union of the current
			     inheritable and permitted capability sets, or the
			     capsh program is operating	 with  CAP_SETPCAP  in
			     its effective set.

       --uid=id		     Force  all	 uid  values  to  equal	 id  using the
			     setuid(2) system call.

       --keep=<0|1>	     In a non-pure capability mode,  the  kernel  pro-
			     vides  liberal  privilege to the super-user. How-
			     ever, it is  normally  the	 case  that  when  the
			     super-user	 changes uid to some lesser user, then
			     capabilities are dropped. For  these  situations,
			     the  kernel  can permit the process to retain its
			     capabilities after a setuid(2) system call.  This
			     feature is known as keep-caps support. The way to
			     activate it using this script is with this	 argu-
			     ment. Setting the value to 1 will cause keep-caps
			     to be active. Setting it to 0  will  cause	 keep-
			     caps  to  deactivate  for the current process. In
			     all  cases,  keep-caps  is	 deactivated  when  an
			     exec()  is	 performed.  See --secbits for ways to
			     disable this feature.

       --secbits=N	     XXX - need to document this feature.

       --chroot=path	     Execute the chroot(2) system call	with  the  new
			     root-directory (/) equal to path.	This operation
			     requires CAP_SYS_CHROOT to be in effect.



       --decode=N	     This is a convenience feature.  If	 you  look  at
			     /proc/1/status  there are some capability related
			     fields of the following form:

			      CapInh:  0000000000000000
			      CapPrm:  ffffffffffffffff
			      CapEff:  fffffffffffffeff
			      CapBnd:  ffffffffffffffff

			     This option provides a  quick  way	 to  decode  a
			     capability	 vector	 represented in this form. For
			     example, the missing capability from this	effec-
			     tive set is 0x0100. By running:

			      capsh --decode=0x0100

			     we	  observe  that	 the  missing  capability  is:

	      Following successful execution the tool  exits  with  status  0.
	      Following an error, the tool immediately exits with status 1.

       Written by Andrew G. Morgan <morgan@kernel.org>.

       Please report bugs to the author.

       libcap(3), getcap(8),setcap(8) and capabilities(7).

libcap 2			  2011-04-24			      CAPSH(1)