Provided by: agedu_9723-1build1_amd64 bug


       agedu - correlate disk usage with last-access times to identify large and disused data


       agedu [ options ] action [action...]


       agedu  scans  a  directory  tree and produces reports about how much disk space is used in
       each directory and subdirectory, and also how that usage  of  disk  space  corresponds  to
       files with last-access times a long time ago.

       In  other words, agedu is a tool you might use to help you free up disk space. It lets you
       see which directories are taking up the most space, as du does; but  unlike  du,  it  also
       distinguishes between large collections of data which are still in use and ones which have
       not been accessed in months or years - for instance, large archives downloaded,  unpacked,
       used  once,  and  never  cleaned up. Where du helps you find what's using your disk space,
       agedu helps you find what's wasting your disk space.

       agedu has several operating modes. In one mode, it scans your disk  and  builds  an  index
       file  containing  a data structure which allows it to efficiently retrieve any information
       it might need. Typically, you would use it in this mode first, and then run it in one of a
       number  of  `query'  modes  to  display  a  report of the disk space usage of a particular
       directory and its subdirectories. Those reports can be produced as plain text  (much  like
       du)  or as HTML. agedu can even run as a miniature web server, presenting each directory's
       HTML report with hyperlinks to let you navigate around the file system to similar  reports
       for other directories.

       So  you  would  typically start using agedu by telling it to do a scan of a directory tree
       and build an index. This is done with a command such as

       $ agedu -s /home/fred

       which will build a large data file called agedu.dat in your current  directory.  (If  that
       current  directory  is  inside /home/fred, don't worry - agedu is smart enough to discount
       its own index file.)

       Having built the index, you would now query it for reports of disk  space  usage.  If  you
       have a graphical web browser, the simplest and nicest way to query the index is by running
       agedu in web server mode:

       $ agedu -w

       which will print (among other messages) a URL on its standard output along the lines of


       (That URL will always begin with `127.', meaning that it's in the localhost address space.
       So only processes running on the same computer can even try to connect to that web server,
       and also there is access control to prevent other users from seeing it  -  see  below  for
       more detail.)

       Now paste that URL into your web browser, and you will be shown a graphical representation
       of the disk usage in /home/fred and its immediate  subdirectories,  with  varying  colours
       used  to  show  the  difference  between  disused and recently-accessed data. Click on any
       subdirectory to descend into it and see a report for its subdirectories in turn; click  on
       parts  of  the pathname at the top of any page to return to higher-level directories. When
       you've finished browsing, you can just press Ctrl-D to send an end-of-file  indication  to
       agedu, and it will shut down.

       After  that, you probably want to delete the data file agedu.dat, since it's pretty large.
       In fact, the command agedu -R will do this for you; and you can chain  agedu  commands  on
       the same command line, so that instead of the above you could have done

       $ agedu -s /home/fred -w -R

       for a single self-contained run of agedu which builds its index, serves web pages from it,
       and cleans it up when finished.

       If you don't have a graphical web browser, you can do text-based queries as  well.  Having
       scanned /home/fred as above, you might run

       $ agedu -t /home/fred

       which  again  gives  a  summary  of  the  disk  usage  in  /home/fred  and  its  immediate
       subdirectories; but this time agedu will print it on standard output,  in  much  the  same
       format  as du. If you then want to find out how much old data is there, you can add the -a
       option to show only files last accessed a certain length of time ago. For example, to show
       only files which haven't been looked at in six months or more:

       $ agedu -t /home/fred -a 6m

       That's  the  essence  of what agedu does. It has other modes of operation for more complex
       situations, and the usual array of configurable options. The following sections contain  a
       complete reference for all its functionality.


       This  section  describes  the  operating modes supported by agedu. Each of these is in the
       form of a command-line option, sometimes with an argument. Multiple operating-mode options
       may appear on the command line, in which case agedu will perform the specified actions one
       after another. For instance, as shown in the previous section, you might want to perform a
       disk scan and immediately launch a web server giving reports from that scan.

       -s directory or --scan directory
              In  this mode, agedu scans the file system starting at the specified directory, and
              indexes the results of the scan into a large data file which other operating  modes
              can query.

              By  default, the scan is restricted to a single file system (since the expected use
              of agedu is that you would probably use it because a particular disk partition  was
              running low on space). You can remove that restriction using the --cross-fs option;
              other configuration options allow  you  to  include  or  exclude  files  or  entire
              subdirectories  from  the  scan.  See  the  next  section  for  full details of the
              configurable options.

              The index file is created with restrictive permissions, in case the file system you
              are scanning contains confidential information in its structure.

              Index  files  are  dependent  on  the  characteristics  of the CPU architecture you
              created them on. You should not expect to be able to move  an  index  file  between
              different  types  of computer and have it continue to work. If you need to transfer
              the results of a disk scan to a different kind of  computer,  see  the  -D  and  -L
              options below.

       -w or --web
              In  this  mode, agedu expects to find an index file already written. It allocates a
              network port, and starts up  a  web  server  on  that  port  which  serves  reports
              generated from the index file. By default it invents its own URL and prints it out.

              The  web  server  runs  until  agedu  receives an end-of-file event on its standard
              input. (The expected usage is that you run it from the  command  line,  immediately
              browse web pages until you're satisfied, and then press Ctrl-D.) To disable the EOF
              behaviour, use the --no-eof option.

              In case the index file  contains  any  confidential  information  about  your  file
              system, the web server protects the pages it serves from access by other people. On
              Linux, this is done transparently by means of  using  /proc/net/tcp  to  check  the
              owner  of  each  incoming  connection;  failing that, the web server will require a
              password to view the reports, and agedu will print  the  password  it  invented  on
              standard output along with the URL.

              Configurable options for this mode let you specify your own address and port number
              to listen on, and also specify your own choice of authentication method  (including
              turning authentication off completely) and a username and password of your choice.

       -t directory or --text directory
              In this mode, agedu generates a textual report on standard output, listing the disk
              usage in the specified directory and all its subdirectories down to a given  depth.
              By  default  that depth is 1, so that you see a report for directory itself and all
              of its immediate subdirectories. You can configure a different depth (or  no  depth
              limit) using -d, described in the next section.

              Used on its own, -t merely lists the total disk usage in each subdirectory; agedu's
              additional ability to distinguish unused from recently-used data is not  activated.
              To activate it, use the -a option to specify a minimum age.

              The directory structure stored in agedu's index file is treated as a set of literal
              strings. This means that you cannot refer to directories by synonyms. So if you ran
              agedu  -s ., then all the path names you later pass to the -t option must be either
              `.' or begin with `./'. Similarly, symbolic links within the directory you  scanned
              will  not  be followed; you must refer to each directory by its canonical, symlink-
              free pathname.

       -R or --remove
              In this mode, agedu deletes its index file. Running just agedu -R  on  its  own  is
              therefore  equivalent  to  typing rm agedu.dat. However, you can also put -R on the
              end of a command line to indicate that agedu should delete its index file after  it
              finishes performing other operations.

       -D or --dump
              In  this  mode,  agedu  reads  an  existing  index  file and produces a dump of its
              contents on standard output. This dump can later be loaded into a new  index  file,
              perhaps on another computer.

       -L or --load
              In  this  mode,  agedu  expects  to  read a dump produced by the -D option from its
              standard input. It constructs an index file from that dump,  exactly  as  it  would
              have if it had read the same data from a disk scan in -s mode.

       -S directory or --scan-dump directory
              In  this  mode,  agedu  will scan a directory tree and convert the results straight
              into a dump on standard output, without generating an index file at all. So running
              agedu  -S  /path  should  produce  equivalent  output to that of agedu -s /path -D,
              except that the latter will produce an index file as a side effect whereas -S  will

              (The  output  will  not  be  exactly identical, due to a difference in treatment of
              last-access times on directories. However, it should be effectively equivalent  for
              most  purposes. See the documentation of the --dir-atime option in the next section
              for further detail.)

       -H directory or --html directory
              In this mode, agedu will generate an HTML report of the disk usage in the specified
              directory  and  its  immediate subdirectories, in the same form that it serves from
              its web server in -w mode.

              By default, a single HTML report will be generated and simply written  to  standard
              output, with no hyperlinks pointing to other similar pages. If you also specify the
              -d option (see below), agedu will instead write out a collection of HTML files with
              hyperlinks between them, and call the top-level file index.html.

       --cgi  In  this  mode,  agedu will run as the bulk of a CGI script which provides the same
              set of web pages as the built-in web server would.  It  will  read  the  usual  CGI
              environment variables, and write CGI-style data to its standard output.

              The actual CGI program itself should be a tiny wrapper around agedu which passes it
              the --cgi option, and also (probably) -f to locate the index file.  agedu  will  do
              everything else.

              No  access  control is performed in this mode: restricting access to CGI scripts is
              assumed to be the job of the web server.

       -h or --help
              Causes agedu to print some help text and terminate immediately.

       -V or --version
              Causes agedu to print its version number and terminate immediately.


       This section describes the various configuration options that affect agedu's operation  in
       one mode or another.

       The following option affects nearly all modes (except -S):

       -f filename or --file filename
              Specifies  the  location  of  the  index file which agedu creates, reads or removes
              depending on its operating  mode.  By  default,  this  is  simply  `agedu.dat',  in
              whatever is the current working directory when you run agedu.

       The following options affect the disk-scanning modes, -s and -S:

       --cross-fs and --no-cross-fs
              These  configure  whether  or  not  the  disk  scan  is  permitted to cross between
              different file systems. The default is  not  to:  agedu  will  normally  skip  over
              subdirectories  on  which  a  different  file  system  is  mounted.  This  makes it
              convenient when you want to free up space on a  particular  file  system  which  is
              running  low.  However,  in  other  circumstances  you  might  wish  to see general
              information about the use of space  no  matter  which  file  system  it's  on  (for
              instance,  if  your  real concern is your backup media running out of space, and if
              your backups do not treat different file systems specially); in that situation, use

              (Note  that this default is the opposite way round from the corresponding option in

       --prune wildcard and --prune-path wildcard
              These cause particular files or directories to be omitted entirely from  the  scan.
              If  agedu's  scan  encounters  a  file or directory whose name matches the wildcard
              provided to the --prune option, it will not include that file  in  its  index,  and
              also if it's a directory it will skip over it and not scan its contents.

              Note  that  in  most Unix shells, wildcards will probably need to be escaped on the
              command line, to prevent the shell from expanding the wildcard  before  agedu  sees

              --prune-path is similar to --prune, except that the wildcard is matched against the
              entire pathname instead of just the filename at the end of it. So  whereas  --prune
              *a*b*  will  match  any  file whose actual name contains an a somewhere before a b,
              --prune-path *a*b* will also match a file whose name contains b and which is inside
              a  directory  containing  an a, or any file inside a directory of that form, and so

       --exclude wildcard and --exclude-path wildcard
              These cause particular files or directories to be omitted from the index,  but  not
              from  the  scan.  If agedu's scan encounters a file or directory whose name matches
              the wildcard provided to the --exclude option, it will not include that file in its
              index  -  but  unlike --prune, if the file in question is a directory it will still
              scan its contents and index them if they are not ruled out themselves by  --exclude

              As  above,  --exclude-path  is  similar  to  --exclude, except that the wildcard is
              matched against the entire pathname.

       --include wildcard and --include-path wildcard
              These cause particular files or directories to be re-included in the index and  the
              scan,  if  they  had previously been ruled out by one of the above exclude or prune
              options. You can interleave include, exclude and prune options as you wish  on  the
              command  line,  and  if  more  than one of them applies to a file then the last one
              takes priority.

              For example, if you wanted to see only the disk space taken up by  MP3  files,  you
              might run

              $ agedu -s . --exclude '*' --include '*.mp3'

              which  will cause everything to be omitted from the scan, but then the MP3 files to
              be put back in. If you then wanted only a subset of  those  MP3s,  you  could  then
              exclude  some  of them again by adding, say, `--exclude-path './queen/*'' (or, more
              efficiently, `--prune ./queen') on the end of that command.

              As with the previous two options, --include-path is  similar  to  --include  except
              that the wildcard is matched against the entire pathname.

       --progress, --no-progress and --tty-progress
              When  agedu  is  scanning  a  directory  tree,  it  will typically print a one-line
              progress report every second showing where it has reached in the scan, so  you  can
              have  some  idea  of  how  much  longer  it will take. (Of course, it can't predict
              exactly how long it will take, since it doesn't know which of  the  directories  it
              hasn't scanned yet will turn out to be huge.)

              By default, those progress reports are displayed on agedu's standard error channel,
              if that channel points to a terminal device. If you  need  to  manually  enable  or
              disable   them,  you  can  use  the  above  three  options  to  do  so:  --progress
              unconditionally  enables  the  progress  reports,   --no-progress   unconditionally
              disables  them,  and  --tty-progress  reverts  to  the  default  behaviour which is
              conditional on standard error being a terminal.

       --dir-atime and --no-dir-atime
              In  normal  operation,  agedu  ignores  the  atimes  (last  access  times)  on  the
              directories  it  scans:  it  only  pays attention to the atimes of the files inside
              those directories. This is because directory atimes tend to be reset by  a  lot  of
              system  administrative  tasks, such as cron jobs which scan the file system for one
              reason or another - or even other invocations of agedu itself, though it  tries  to
              avoid  modifying  any  atimes if possible. So the literal atimes on directories are
              typically not representative of how long ago the data in question was last accessed
              with real intent to use that data in particular.

              Instead,  agedu  makes up a fake atime for every directory it scans, which is equal
              to the newest atime of any file in or below that directory (or the directory's last
              modification  time,  whichever is newest). This is based on the assumption that all
              important accesses to directories are actually accesses to the files  inside  those
              directories,  so  that  when  any  file is accessed all the directories on the path
              leading to it should be considered to have been accessed as well.

              In unusual cases it is possible that a directory itself might embody important data
              which is accessed by reading the directory. In that situation, agedu's atime-faking
              policy will misreport the directory as disused. In the  unlikely  event  that  such
              directories  form  a  significant  part of your disk space usage, you might want to
              turn off the faking. The --dir-atime option does this: it causes the disk  scan  to
              read the original atimes of the directories it scans.

              The  faking of atimes on directories also requires a processing pass over the index
              file after the main disk scan is complete. --dir-atime also turns  this  pass  off.
              Hence, this option affects the -L option as well as -s and -S.

              (The  previous section mentioned that there might be subtle differences between the
              output of agedu -s /path -D and agedu -S /path. This is why. Doing a scan  with  -s
              and  then  dumping  it with -D will dump the fully faked atimes on the directories,
              whereas doing a scan-to-dump with -S  will  dump  only  partially  faked  atimes  -
              specifically,  each  directory's  last  modification  time  -  since the subsequent
              processing pass will not have had a chance to take place. However,  loading  either
              of  the resulting dump files with -L will perform the atime-faking processing pass,
              leading to the same data in the index file in each case. In normal usage it  should
              be safe to ignore all of this complexity.)

              This  option causes agedu to index files by their last modification time instead of
              their last access time. You might want to use this if your last access  times  were
              completely useless for some reason: for example, if you had recently searched every
              file on your system, the system would have lost  all  the  information  about  what
              files  you  hadn't recently accessed before then. Using this option is liable to be
              less effective at finding genuinely wasted space than the normal mode (that is,  it
              will  be  more  likely to flag things as disused when they're not, so you will have
              more candidates to go through by hand looking for data you don't need), but may  be
              better than nothing if your last-access times are unhelpful.

              Another  use  for  this  mode might be to find recently created large data. If your
              disk has been gradually filling up for years, the default mode of  agedu  will  let
              you  find  unused  data  to  delete;  but if you know your disk had plenty of space
              recently and now it's suddenly full, and you suspect that some  rogue  program  has
              left a large core dump or output file, then agedu --mtime might be a convenient way
              to locate the culprit.

       The following option affects all the modes that generate reports: the web server mode  -w,
       the stand-alone HTML generation mode -H and the text report mode -t.

              This  option causes agedu's reports to list the individual files in each directory,
              instead  of  just  giving  a  combined  report  for  everything  that's  not  in  a

       The following option affects the text report mode -t.

       -a age or --age age
              This  option tells agedu to report only files of at least the specified age. An age
              is specified as a number, followed by one of `y' (years), `m' (months), `w' (weeks)
              or `d' (days). (This syntax is also used by the -r option.) For example, -a 6m will
              produce a text report which includes only files at least six months old.

       The following options affect the stand-alone HTML generation mode -H and the  text  report
       mode -t.

       -d depth or --depth depth
              This  option  controls  the maximum depth to which agedu recurses when generating a
              text or HTML report.

              In text mode, the default is 1, meaning that the report will include the  directory
              given  on  the command line and all of its immediate subdirectories. A depth of two
              includes another level below that, and so on;  a  depth  of  zero  means  only  the
              directory on the command line.

              In  HTML mode, specifying this option switches agedu from writing out a single HTML
              file to writing out multiple files which link to each other. A  depth  of  1  means
              agedu  will write out an HTML file for the given directory and also one for each of
              its immediate subdirectories.

              If you want agedu to recurse as deeply as possible, give the special word `max'  as
              an argument to -d.

       -o filename or --output filename
              This  option is used to specify an output file for agedu to write its report to. In
              text mode or single-file HTML mode, the argument is treated as the name of a  file.
              In multiple-file HTML mode, the argument is treated as the name of a directory: the
              directory will be created if it does not already exist, and the output  HTML  files
              will be created inside it.

       The  following  options  affect  the web server mode -w, and in some cases also the stand-
       alone HTML generation mode -H:

       -r age range or --age-range age range
              The HTML reports produced by agedu use a range of colours to indicate how long  ago
              data  was  last  accessed, running from red (representing the most disused data) to
              green (representing the newest). By default, the lengths of time represented by the
              two  ends  of that spectrum are chosen by examining the data file to see what range
              of ages appears in it. However, you might want to set your own limits, and you  can
              do this using -r.

              The argument to -r consists of a single age, or two ages separated by a minus sign.
              An age is a number, followed by one of `y' (years), `m' (months),  `w'  (weeks)  or
              `d' (days). (This syntax is also used by the -a option.) The first age in the range
              represents the oldest data, and will be coloured red in the HTML;  the  second  age
              represents  the newest, coloured green. If the second age is not specified, it will
              default to zero (so that green means data which has been accessed just now).

              For example, -r 2y will mark data in red if it has been unused  for  two  years  or
              more, and green if it has been accessed just now. -r 2y-3m will similarly mark data
              red if it has been unused for two years or more, but will mark it green if  it  has
              been accessed three months ago or later.

       --address addr[:port]
              Specifies  the  network  address  and port number on which agedu should listen when
              running its web server. If you want agedu to listen for connections coming in  from
              any  source,  specify  the  address as the special value ANY. If the port number is
              omitted, an arbitrary unused port will be chosen for you and displayed.

              If you specify this option, agedu will not print its URL on standard output  (since
              you are expected to know what address you told it to listen to).

       --auth auth-type
              Specifies  how  agedu should control access to the web pages it serves. The options
              are as follows:

              magic  This option only works on Linux, and only when the  incoming  connection  is
                     from  the  same machine that agedu is running on. On Linux, the special file
                     /proc/net/tcp contains a list of network connections currently known to  the
                     operating system kernel, including which user id created them. So agedu will
                     look up each incoming connection in that file, and allow access if it  comes
                     from  the  same  user  id under which agedu itself is running. Therefore, in
                     agedu's normal web server mode, you  can  safely  run  it  on  a  multi-user
                     machine and no other user will be able to read data out of your index file.

              basic  In  this  mode, agedu will use HTTP Basic authentication: the user will have
                     to provide a username and password via their browser.  agedu  will  normally
                     make  up  a  username and password for the purpose, but you can specify your
                     own; see below.

              none   In this mode, the web server is unauthenticated: anyone connecting to it has
                     full  access  to the reports generated by agedu. Do not do this unless there
                     is nothing confidential at all in your index file, or unless you are certain
                     that nobody but you can run processes on your computer.

                     This  is  the  default  mode if you do not specify one of the above. In this
                     mode, agedu will attempt to  use  Linux  magic  authentication,  but  if  it
                     detects  at startup time that /proc/net/tcp is absent or non-functional then
                     it will fall back to using HTTP Basic authentication and invent a user  name
                     and password.

       --auth-file filename or --auth-fd fd
              When  agedu  is using HTTP Basic authentication, these options allow you to specify
              your own user name and password. If you specify --auth-file,  these  will  be  read
              from  the specified file; if you specify --auth-fd they will instead be read from a
              given file descriptor which you should have arranged to pass to  agedu.  In  either
              case,  the  authentication  details  should  consist of the username, followed by a
              colon, followed by the password, followed immediately by end of file  (no  trailing
              newline, or else it will be considered part of the password).

       --title title
              Specify  the  string that appears at the start of the <title> section of the output
              HTML pages. The default is `agedu'. This title is followed by a colon and then  the
              path  you're  viewing  within the index file. You might use this option if you were
              serving agedu reports for several different servers and wanted to make  it  clearer
              which one a user was looking at.

              Stop  agedu  in  web server mode from looking for end-of-file on standard input and
              treating it as a signal to terminate.


       The data file is pretty large. The core of agedu is the tree-based data structure it  uses
       in  its  index  in  order to efficiently perform the queries it needs; this data structure
       requires O(N log N) storage. This is larger than you might expect; a scan of my  own  home
       directory,  containing  half  a  million  files  and  directories  and about 20Gb of data,
       produced an index file over 60Mb in size. Furthermore, since the data file must be memory-
       mapped during most processing, it can never grow larger than available address space, so a
       really big filesystem may need to be indexed on a 64-bit computer. (This is one reason for
       the existence of the -D and -L options: you can do the scanning on the machine with access
       to the filesystem, and the indexing on a machine big enough to handle it.)

       The data structure also does not usefully permit access control within the data  file,  so
       it  would  be  difficult  -  even given the willingness to do additional coding - to run a
       system-wide agedu scan on a cron job and serve the right subset of reports to each user.

       In certain circumstances, agedu can report false positives  (reporting  files  as  disused
       which  are  in fact in use) as well as the more benign false negatives (reporting files as
       in use which are not). This arises when a file is, semantically speaking,  `read'  without
       actually  being  physically  read. Typically this occurs when a program checks whether the
       file's mtime has changed and only bothers re-reading it if it has; programs which do  this
       include  rsync(1)  and  make(1). Such programs will fail to update the atime of unmodified
       files despite depending on their continued existence; a directory full of such files  will
       be reported as disused by agedu even in situations where deleting them will cause trouble.

       Finally, of course, agedu's normal usage mode depends critically on the OS providing last-
       access times which are at least approximately right. So a file system mounted with Linux's
       `noatime'  option,  or  the  equivalent  on  any  other  OS, will not give useful results!
       (However, the Linux mount option `relatime',  which  distributions  now  tend  to  use  by
       default,  should be fine for all but specialist purposes: it reduces the accuracy of last-
       access times so that they might be wrong by up to 24 hours,  but  if  you're  looking  for
       files that have been unused for months or years, that's not a problem.)


       agedu is free software, distributed under the MIT licence. Type agedu --licence to see the
       full licence text.