NAME

       augprint - create an idempotent augtool script for a given file

SYNOPSIS

       augprint [--pretty|-p] [--regexp[=n]|-r[n]] [--noseq|-s] [--verbose|-v] [--lens name|-l
       name] [--target /target|-t /target] FILE

DESCRIPTION

       augprint creates an augtool script for a given FILE consisting primarily of "set"
       commands.

       The resulting augtool script is designed to be idempotent, and will not result in any
       changes when applied to the original file.

       augprint replaces each numbered location in the tree with a path-expression that uniquely
       identifies the position using the values within that position.

       This makes the path-expression independant of the position-number, and thereby applicable
       to files which in which the same data may exist at an alternate position-number

       See "Examples" for sample output

   Regexp output
       By default augprint produces path-expressions made up of simple equality "=" comparisions

         set /files/etc/hosts/seq::*[ipaddr='127.0.0.1']/ipaddr '127.0.0.1'

       The option --regexp changes the output to produce regular expression comparisions

         set /files/etc/hosts/seq::*[ipaddr=~regexp('127\\.0\\..*')]/ipaddr '127.0.0.1'

       The minimum length N of the regular expression can be specified using "--regexp=N"

       augprint will choose a longer regular expression than N if multiple values would match
       using the N character regular expression.

   Limitations
       Append-only

       The output is based primarily on set operations.  The set operation can only:

       a) change an existing value in-situ

       b) append a new value after the last position in the group

       This means that when an entry is re-created, it may not be in the same position as
       originally intended.  ie if the entry for 192.0.2.3 does not already exist, it will be
       created as the last entry in /etc/hosts

       Often, such out-of-sequence entries will not matter to the resulting configuration file.
       If it does matter, further manual editing of the "augtool" script will be required.

       Repeated Values

       augprint is not always successful in finding a path-expression which is unique to a
       position.  In this case augprint appends a position to an expression which is not unique

       This occurs in particular if there are repeated values within the file.

       For an /etc/hosts file of

         #------
         192.0.2.3   defaultdns
         #------

       augprint would produce the output

         set /files/etc/hosts/#comment[.='--------'][1] '--------'
         set /files/etc/hosts/seq::*[ipaddr='192.0.2.3']/ipaddr '192.0.2.3'
         set /files/etc/hosts/seq::*[ipaddr='192.0.2.3']/canonical 'defaultdns'
         set /files/etc/hosts/#comment[.='--------'][2] '--------'

       Notice how "#comment" paths have "[1]" and "[2]" appended respectively to the "[expr]"

       Other paths which do have unique path-expressions are not directly affected

OPTIONS

       -v, --verbose
           Include the original numbered paths as comments in the output

       -p, --pretty
           Create more readable output by adding spaces and empty lines

       -r, -rN, --regexp, --regexp=N
           Generate regular expressions to match values, using a minumum length of N characters
           from the value

           N  can be omitted and defaults to 8

       -l, --lens=LENS
           Use LENS for the given file; without this option, augprint uses the default lens for
           the file

       -t targetfile, --target=targetfile
           Generate the script for the FILE specified as if its path was really targetfile

           This will apply the lens corresponding to targetfile to FILE and modifying the
           resulting path-expressions of FILE to correspond to targetfile

           targetfile must be the full path name, starting with a '/'

           See "Examples" for how --target can be used in practice

       -s, --noseq
           Do not use "seq::*" in the output, use "*" instead.  For example

             set /files/etc/hosts/*[ipaddr='127.0.0.1']/ipaddr '127.0.0.1'

           IMPORTANT: The resulting output will no longer create a new entry for 127.0.0.1 if
           none already exists. The "--noseq" option exists so that the resulting paths can be
           used with augeas versions prior to 1.13.0 (subject to this limitation)

EXAMPLES

       These examples use the following /etc/hosts file as the FILE

         127.0.0.1   localhost localhost.localdomain localhost4 localhost4.localdomain4
         192.0.2.3   dns-a
         192.0.2.4   dns-b

       The output from "augtool 'print /files/etc/hosts'" would be

         /files/etc/hosts
         /files/etc/hosts/1
         /files/etc/hosts/1/ipaddr = "127.0.0.1"
         /files/etc/hosts/1/canonical = "localhost"
         /files/etc/hosts/1/alias[1] = "localhost.localdomain"
         /files/etc/hosts/1/alias[2] = "localhost4"
         /files/etc/hosts/1/alias[3] = "localhost4.localdomain4"
         /files/etc/hosts/2
         /files/etc/hosts/2/ipaddr = "192.0.2.3"
         /files/etc/hosts/2/canonical = "dns-a"
         /files/etc/hosts/3
         /files/etc/hosts/3/ipaddr = "192.0.2.4"
         /files/etc/hosts/3/canonical = "dns-b"

   Default output
       "augprint /etc/hosts"

         set /files/etc/hosts/seq::*[ipaddr='127.0.0.1']/ipaddr '127.0.0.1'
         set /files/etc/hosts/seq::*[ipaddr='127.0.0.1']/canonical 'localhost'
         set /files/etc/hosts/seq::*[ipaddr='127.0.0.1']/alias[.='localhost.localdomain'] 'localhost.localdomain'
         set /files/etc/hosts/seq::*[ipaddr='127.0.0.1']/alias[.='localhost4'] 'localhost4'
         set /files/etc/hosts/seq::*[ipaddr='127.0.0.1']/alias[.='localhost4.localdomain4'] 'localhost4.localdomain4'
         set /files/etc/hosts/seq::*[ipaddr='192.0.2.3']/ipaddr '192.0.2.3'
         set /files/etc/hosts/seq::*[ipaddr='192.0.2.3']/canonical 'dns-a'
         set /files/etc/hosts/seq::*[ipaddr='192.0.2.4']/ipaddr '192.0.2.4'
         set /files/etc/hosts/seq::*[ipaddr='192.0.2.4']/canonical 'dns-b'

   Verbose output
       "augprint --verbose /etc/hosts"

         #   /files/etc/hosts
         #   /files/etc/hosts/1
         #   /files/etc/hosts/1/ipaddr  '127.0.0.1'
         set /files/etc/hosts/seq::*[ipaddr='127.0.0.1']/ipaddr '127.0.0.1'
         #   /files/etc/hosts/1/canonical  'localhost'
         set /files/etc/hosts/seq::*[ipaddr='127.0.0.1']/canonical 'localhost'
         #   /files/etc/hosts/1/alias[1]  'localhost.localdomain'
         set /files/etc/hosts/seq::*[ipaddr='127.0.0.1']/alias[.='localhost.localdomain'] 'localhost.localdomain'
         ...

   Rexexp output
       "augprint --regexp=4 /etc/hosts"

         set /files/etc/hosts/seq::*[ipaddr=~regexp('127\\..*')]/ipaddr '127.0.0.1'
         set /files/etc/hosts/seq::*[ipaddr=~regexp('127\\..*')]/canonical 'localhost'
         set /files/etc/hosts/seq::*[ipaddr=~regexp('127\\..*')]/alias[.=~regexp('localhost\\..*')] 'localhost.localdomain'
         set /files/etc/hosts/seq::*[ipaddr=~regexp('127\\..*')]/alias[.=~regexp('localhost4')] 'localhost4'
         set /files/etc/hosts/seq::*[ipaddr=~regexp('127\\..*')]/alias[.=~regexp('localhost4\\..*')] 'localhost4.localdomain4'
         set /files/etc/hosts/seq::*[ipaddr=~regexp('192\\.0\\.2\\.3')]/ipaddr '192.0.2.3'
         set /files/etc/hosts/seq::*[ipaddr=~regexp('192\\.0\\.2\\.3')]/canonical 'dns-a'
         set /files/etc/hosts/seq::*[ipaddr=~regexp('192\\.0\\.2\\.4')]/ipaddr '192.0.2.4'
         set /files/etc/hosts/seq::*[ipaddr=~regexp('192\\.0\\.2\\.4')]/canonical 'dns-b'

       Note that although a minimum length of 4 has been specified, augprint will choose longer
       regular expressions as needed to ensure a unique match.

   Using --lens
       If a file is not assocatiated with a lens by default, --lens lensname can be used to
       specify a lens.

       When --lens  is specified, the output is prefixed with suitable "transform" and
       "load-file" statements, as required to complete the augtool script, and a setm statement
       to exclude other autoloaded lenses.

       "augprint --lens shellvars /etc/skel/.bashrc"

         setm /augeas/load/*[incl='/etc/skel/.bashrc' and label() != 'shellvars']/excl '/etc/skel/.bashrc'
         transform shellvars incl /etc/skel/.bashrc
         load-file /etc/skel/.bashrc
         set /files/etc/skel/.bashrc/#comment[.='.bashrc'] '.bashrc'
         set /files/etc/skel/.bashrc/#comment[.='Source global definitions'] 'Source global definitions'
         set /files/etc/skel/.bashrc/@if[.='[ -f /etc/bashrc ]'] '[ -f /etc/bashrc ]'
         set /files/etc/skel/.bashrc/@if[.='[ -f /etc/bashrc ]']/.source '/etc/bashrc'
         set /files/etc/skel/.bashrc/#comment[.='User specific environment'] 'User specific environment'
         ...

       The lenses "simplelines"  "shellvars" are most commonly useful as lenses for files that do
       not have a specific lens

   Using --target
       In order to prepare an augtool script intended for a given file, it may be desired to copy
       the file to another location, rather than editting the original file.

       The option --target simplifies this process.

       a) copy /etc/hosts to a new location

          cp /etc/hosts ~

       b) edit ~/hosts to suit

          echo '192.0.2.7   defaultdns' >> ~/hosts

       c) Run "augprint" as follows

          augprint --target /etc/hosts ~/hosts

       d) Copy the relevant part of the output to an augtool script or other Augeas client

          set /files/etc/hosts/seq::*[ipaddr='192.0.2.7']/ipaddr '192.0.2.7'
          set /files/etc/hosts/seq::*[ipaddr='192.0.2.7']/canonical 'defaultdns'

       Notice that "augprint" has generated paths corresponding to --target (/etc/hosts) instead
       of the FILE argument (~/hosts)

ENVIRONMENT VARIABLES

       AUGEAS_ROOT
           The effective file system root, defaults to '/'.

       AUGEAS_LENS_LIB
           Colon separated list of directories with lenses. Directories specified here are
           searched before the default directories /usr/share/augeas/lenses and
           /usr/share/augeas/lenses/dist

EXIT STATUS

       The exit status is 0 when the command was successful and 1 if any error occurred.

FILES

       Lenses and schema definitions in /usr/share/augeas/lenses and
       /usr/share/augeas/lenses/dist

AUTHOR

       George Hansper <george@hansper.id.au>

COPYRIGHT AND LICENSE

       Copyright 2022 George Hansper

       Augeas (and augprint) are distributed under the GNU Lesser General Public License (LGPL),
       version 2.1

SEE ALSO

       augtool(1)

       Augeas project homepage <https://www.augeas.net/>

       Augeas path expressions <https://github.com/hercules-team/augeas/wiki/Path-expressions>