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runat(1)                         User Commands                        runat(1)



NAME
       runat - execute command in extended attribute name space

SYNOPSIS
       /usr/bin/runat file [command]

DESCRIPTION
       The  runat utility is used to execute shell commands in a file's hidden
       attribute directory. Effectively,  this  utility  changes  the  current
       working  directory to be the hidden attribute directory associated with
       the file argument and then executes the specified command in the bourne
       shell  (/bin/sh).  If  no  command argument is provided, an interactive
       shell is spawned. The environment variable $SHELL defines the shell  to
       be  spawned. If this variable is undefined, the default shell, /bin/sh,
       is used.

       The file argument can be any file, including a directory, that can sup-
       port  extended  attributes. It is not necessary that this file have any
       attributes, or be prepared in any way, before invoking the  runat  com-
       mand.

OPERANDS
       The following operands are supported:

       file            Any  file,  including  a  directory,  that  can support
                       extended attributes.



       command         The command to be executed in an attribute directory.



ERRORS
       A non-zero exit status will be returned if runat cannot access the file
       argument, or the file argument does not support extended attributes.

USAGE
       See fsattr(5) for a detailed description of extended file attributes.

       The  process context created by the runat command has its current work-
       ing directory  set  to  the  hidden  directory  containing  the  file's
       extended  attributes.  The  parent  of  this directory (the ".." entry)
       always refers to the file provided on the command line. As such, it may
       not  be a directory. Therefore, commands (such as pwd) that depend upon
       the parent entry being well-formed (that is, referring to a  directory)
       may fail.

       In the absence of the command argument, runat will spawn a new interac-
       tive shell with its current working directory set to  be  the  provided
       file's hidden attribute directory. Notice that some shells (such as zsh
       and tcsh) are not well behaved when  the  directory  parent  is  not  a
       directory,  as  described  above.  These shells should not be used with
       runat.

EXAMPLES
       Example 1: Using runat to list extended attributes on a file

       example% runat file.1 ls -l
       example% runat file.1 ls

       Example 2: Creating extended attributes

       example% runat file.2 cp /tmp/attrdata attr.1
       example% runat file.2 cat /tmp/attrdata >> attr.1

       Example 3: Copying an attribute from one file to another

       example% runat file.2 cat attr.1 | runat file.1 "cat >> attr.1"

       Example 4: Using runat to spawn an interactive shell

       example% runat file.3 /bin/sh

       This spawns a new shell in the attribute directory for  file.3.  Notice
       that  the  shell will not be able to determine what your current direc-
       tory is. To leave the attribute  directory,  either  exit  the  spawned
       shell or change directory (cd) using an absolute path.

       Recommended methods for performing basic attribute operations:

       display

           runat file ls [options]



       read

           runat file cat attribute



       create/modify

           runat file cp absolute-file-path attribute



       delete

           runat file rm attribute



       permission changes


           runat file chmod mode attribute
           runat file chgrp group attribute
           runat file chown owner attribute



       interactive shell


           runat file /bin/sh
            or set your $SHELL to /bin/sh and
           runat file



       The  above  list  includes  commands that are known to work with runat.
       While many other commands may work, there  is  no  guarantee  that  any
       beyond  this  list  will work. Any command that relies on being able to
       determine its current working directory is likely to fail. Examples  of
       such commands follow:

       Example 5: Using man in an attribute directory

       example% runat file.1 man runat
       getcwd: Not a directory

       Example 6: Spawning a tcsh shell in an attribute directory

       example% runat file.3 /usr/bin/tcsh
       tcsh: Not a directory
       tcsh: Trying to start from "/home/user"

       A  new  tcsh  shell has been spawned with the current working directory
       set to the user's home directory.

       Example 7: Spawning a zsh shell in an attribute directory

       example% runat file.3 /usr/bin/zsh
       example%

       While the command appears to have worked, zsh has actually just changed
       the  current  working  directory  to  '/'.  This  can  be seen by using
       /bin/pwd:

       example% /bin/pwd
       /

ENVIRONMENT VARIABLES
       SHELL           Specifies the command shell to be invoked by runat.



EXIT STATUS
       The following exit values are returned:

       125      The attribute directory of the file  referenced  by  the  file
                argument cannot be accessed.



       126      The exec of the provided command argument failed.



       Otherwise,  the  exit  status  returned is the exit status of the shell
       invoked to execute the provided command.

ATTRIBUTES
       See attributes(5) for descriptions of the following attributes:


       tab()    allbox;    cw(2.750000i)|     cw(2.750000i)     lw(2.750000i)|
       lw(2.750000i).    ATTRIBUTE   TYPEATTRIBUTE  VALUE  AvailabilitySUNWcsu
       CSIEnabled Interface StabilityEvolving


SEE ALSO
       open(2), attributes(5), fsattr(5)

NOTES
       It is not always obvious why a command fails in runat when it is unable
       to determine the current working directory. The errors resulting can be
       confusing and ambiguous (see the tcsh and zsh examples above).



SunOS 5.10                        22 Jun 2001                         runat(1)