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1 | \cfg{man-identity}{agedu}{1}{2008-11-02}{Simon Tatham}{Simon Tatham} |
2 | |
3 | \define{dash} \u2013{-} |
4 | |
5 | \title Man page for \cw{agedu} |
6 | |
7 | \U NAME |
8 | |
61df92dc |
9 | \cw{agedu} \dash correlate disk usage with last-access times to |
10 | identify large and disused data |
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11 | |
12 | \U SYNOPSIS |
13 | |
14 | \c agedu [ options ] action [action...] |
15 | \e bbbbb iiiiiii iiiiii iiiiii |
16 | |
17 | \U DESCRIPTION |
18 | |
19 | \cw{agedu} scans a directory tree and produces reports about how |
20 | much disk space is used in each directory and subdirectory, and also |
21 | how that usage of disk space corresponds to files with last-access |
22 | times a long time ago. |
23 | |
24 | In other words, \cw{agedu} is a tool you might use to help you free |
25 | up disk space. It lets you see which directories are taking up the |
26 | most space, as \cw{du} does; but unlike \cw{du}, it also |
27 | distinguishes between large collections of data which are still in |
28 | use and ones which have not been accessed in months or years \dash |
29 | for instance, large archives downloaded, unpacked, used once, and |
30 | never cleaned up. Where \cw{du} helps you find what's using your |
31 | disk space, \cw{agedu} helps you find what's \e{wasting} your disk |
32 | space. |
33 | |
34 | \cw{agedu} has several operating modes. In one mode, it scans your |
35 | disk and builds an index file containing a data structure which |
36 | allows it to efficiently retrieve any information it might need. |
37 | Typically, you would use it in this mode first, and then run it in |
38 | one of a number of \q{query} modes to display a report of the disk |
39 | space usage of a particular directory and its subdirectories. Those |
40 | reports can be produced as plain text (much like \cw{du}) or as |
41 | HTML. \cw{agedu} can even run as a miniature web server, presenting |
42 | each directory's HTML report with hyperlinks to let you navigate |
43 | around the file system to similar reports for other directories. |
44 | |
45 | So you would typically start using \cw{agedu} by telling it to do a |
46 | scan of a directory tree and build an index. This is done with a |
47 | command such as |
48 | |
49 | \c $ agedu -s /home/fred |
50 | \e bbbbbbbbbbbbbbbbbbb |
51 | |
52 | which will build a large data file called \c{agedu.dat} in your |
53 | current directory. (If that current directory is \e{inside} |
54 | \cw{/home/fred}, don't worry \dash \cw{agedu} is smart enough to |
55 | discount its own index file.) |
56 | |
57 | Having built the index, you would now query it for reports of disk |
58 | space usage. If you have a graphical web browser, the simplest and |
59 | nicest way to query the index is by running \cw{agedu} in web server |
60 | mode: |
61 | |
62 | \c $ agedu -w |
63 | \e bbbbbbbb |
64 | |
65 | which will print (among other messages) a URL on its standard output |
66 | along the lines of |
67 | |
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68 | \c URL: http://127.0.0.1:48638/ |
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69 | |
70 | (That URL will always begin with \cq{127.}, meaning that it's in the |
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71 | \cw{localhost} address space. So only processes running on the same |
72 | computer can even try to connect to that web server, and also there |
73 | is access control to prevent other users from seeing it \dash see |
74 | below for more detail.) |
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75 | |
76 | Now paste that URL into your web browser, and you will be shown a |
77 | graphical representation of the disk usage in \cw{/home/fred} and |
78 | its immediate subdirectories, with varying colours used to show the |
79 | difference between disused and recently-accessed data. Click on any |
80 | subdirectory to descend into it and see a report for its |
81 | subdirectories in turn; click on parts of the pathname at the top of |
82 | any page to return to higher-level directories. When you've finished |
83 | browsing, you can just press Ctrl-D to send an end-of-file |
84 | indication to \cw{agedu}, and it will shut down. |
85 | |
86 | After that, you probably want to delete the data file |
87 | \cw{agedu.dat}, since it's pretty large. In fact, the command |
88 | \cw{agedu -R} will do this for you; and you can chain \cw{agedu} |
89 | commands on the same command line, so that instead of the above you |
90 | could have done |
91 | |
92 | \c $ agedu -s /home/fred -w -R |
93 | \e bbbbbbbbbbbbbbbbbbbbbbbbb |
94 | |
95 | for a single self-contained run of \cw{agedu} which builds its |
96 | index, serves web pages from it, and cleans it up when finished. |
97 | |
98 | If you don't have a graphical web browser, you can do text-based |
99 | queries as well. Having scanned \cw{/home/fred} as above, you might |
100 | run |
101 | |
102 | \c $ agedu -t /home/fred |
103 | \e bbbbbbbbbbbbbbbbbbb |
104 | |
105 | which again gives a summary of the disk usage in \cw{/home/fred} and |
106 | its immediate subdirectories; but this time \cw{agedu} will print it |
107 | on standard output, in much the same format as \cw{du}. If you then |
108 | want to find out how much \e{old} data is there, you can add the |
109 | \cw{-a} option to show only files last accessed a certain length of |
110 | time ago. For example, to show only files which haven't been looked |
111 | at in six months or more: |
112 | |
113 | \c $ agedu -t /home/fred -a 6m |
114 | \e bbbbbbbbbbbbbbbbbbbbbbbbb |
115 | |
116 | That's the essence of what \cw{agedu} does. It has other modes of |
117 | operation for more complex situations, and the usual array of |
118 | configurable options. The following sections contain a complete |
119 | reference for all its functionality. |
120 | |
121 | \U OPERATING MODES |
122 | |
123 | This section describes the operating modes supported by \cw{agedu}. |
124 | Each of these is in the form of a command-line option, sometimes |
125 | with an argument. Multiple operating-mode options may appear on the |
126 | command line, in which case \cw{agedu} will perform the specified |
127 | actions one after another. For instance, as shown in the previous |
128 | section, you might want to perform a disk scan and immediately |
129 | launch a web server giving reports from that scan. |
130 | |
131 | \dt \cw{-s} \e{directory} or \cw{--scan} \e{directory} |
132 | |
133 | \dd In this mode, \cw{agedu} scans the file system starting at the |
134 | specified directory, and indexes the results of the scan into a |
135 | large data file which other operating modes can query. |
136 | |
137 | \lcont{ |
138 | |
139 | By default, the scan is restricted to a single file system (since |
140 | the expected use of \cw{agedu} is that you would probably use it |
141 | because a particular disk partition was running low on space). You |
142 | can remove that restriction using the \cw{--cross-fs} option; other |
143 | configuration options allow you to include or exclude files or |
144 | entire subdirectories from the scan. See the next section for full |
145 | details of the configurable options. |
146 | |
147 | The index file is created with restrictive permissions, in case the |
148 | file system you are scanning contains confidential information in |
149 | its structure. |
150 | |
151 | Index files are dependent on the characteristics of the CPU |
152 | architecture you created them on. You should not expect to be able |
153 | to move an index file between different types of computer and have |
154 | it continue to work. If you need to transfer the results of a disk |
155 | scan to a different kind of computer, see the \cw{-D} and \cw{-L} |
156 | options below. |
157 | |
158 | } |
159 | |
160 | \dt \cw{-w} or \cw{--web} |
161 | |
162 | \dd In this mode, \cw{agedu} expects to find an index file already |
163 | written. It allocates a network port, and starts up a web server on |
164 | that port which serves reports generated from the index file. By |
165 | default it invents its own URL and prints it out. |
166 | |
167 | \lcont{ |
168 | |
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169 | The web server runs until \cw{agedu} receives an end-of-file event on |
170 | its standard input. (The expected usage is that you run it from the |
171 | command line, immediately browse web pages until you're satisfied, and |
172 | then press Ctrl-D.) To disable the EOF behaviour, use the |
173 | \cw{--no-eof} option. |
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174 | |
175 | In case the index file contains any confidential information about |
176 | your file system, the web server protects the pages it serves from |
177 | access by other people. On Linux, this is done transparently by |
178 | means of using \cw{/proc/net/tcp} to check the owner of each |
179 | incoming connection; failing that, the web server will require a |
180 | password to view the reports, and \cw{agedu} will print the password |
181 | it invented on standard output along with the URL. |
182 | |
183 | Configurable options for this mode let you specify your own address |
184 | and port number to listen on, and also specify your own choice of |
185 | authentication method (including turning authentication off |
186 | completely) and a username and password of your choice. |
187 | |
188 | } |
189 | |
190 | \dt \cw{-t} \e{directory} or \cw{--text} \e{directory} |
191 | |
192 | \dd In this mode, \cw{agedu} generates a textual report on standard |
193 | output, listing the disk usage in the specified directory and all |
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194 | its subdirectories down to a given depth. By default that depth is |
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195 | 1, so that you see a report for \e{directory} itself and all of its |
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196 | immediate subdirectories. You can configure a different depth (or no |
197 | depth limit) using \cw{-d}, described in the next section. |
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198 | |
199 | \lcont{ |
200 | |
201 | Used on its own, \cw{-t} merely lists the \e{total} disk usage in |
202 | each subdirectory; \cw{agedu}'s additional ability to distinguish |
203 | unused from recently-used data is not activated. To activate it, use |
204 | the \cw{-a} option to specify a minimum age. |
205 | |
206 | The directory structure stored in \cw{agedu}'s index file is treated |
207 | as a set of literal strings. This means that you cannot refer to |
208 | directories by synonyms. So if you ran \cw{agedu -s .}, then all the |
209 | path names you later pass to the \cw{-t} option must be either |
210 | \cq{.} or begin with \cq{./}. Similarly, symbolic links within the |
211 | directory you scanned will not be followed; you must refer to each |
212 | directory by its canonical, symlink-free pathname. |
213 | |
214 | } |
215 | |
216 | \dt \cw{-R} or \cw{--remove} |
217 | |
218 | \dd In this mode, \cw{agedu} deletes its index file. Running just |
219 | \cw{agedu -R} on its own is therefore equivalent to typing \cw{rm |
220 | agedu.dat}. However, you can also put \cw{-R} on the end of a |
221 | command line to indicate that \cw{agedu} should delete its index |
222 | file after it finishes performing other operations. |
223 | |
224 | \dt \cw{-D} or \cw{--dump} |
225 | |
226 | \dd In this mode, \cw{agedu} reads an existing index file and |
227 | produces a dump of its contents on standard output. This dump can |
228 | later be loaded into a new index file, perhaps on another computer. |
229 | |
230 | \dt \cw{-L} or \cw{--load} |
231 | |
232 | \dd In this mode, \cw{agedu} expects to read a dump produced by the |
233 | \cw{-D} option from its standard input. It constructs an index file |
234 | from that dump, exactly as it would have if it had read the same |
235 | data from a disk scan in \cw{-s} mode. |
236 | |
237 | \dt \cw{-S} \e{directory} or \cw{--scan-dump} \e{directory} |
238 | |
239 | \dd In this mode, \cw{agedu} will scan a directory tree and convert |
240 | the results straight into a dump on standard output, without |
241 | generating an index file at all. So running \cw{agedu -S /path} |
242 | should produce equivalent output to that of \cw{agedu -s /path -D}, |
243 | except that the latter will produce an index file as a side effect |
244 | whereas \cw{-S} will not. |
245 | |
246 | \lcont{ |
247 | |
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248 | (The output will not be exactly \e{identical}, due to a |
249 | difference in treatment of last-access times on directories. |
250 | However, it should be effectively equivalent for most purposes. See |
251 | the documentation of the \cw{--dir-atime} option in the next section |
252 | for further detail.) |
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253 | |
254 | } |
255 | |
256 | \dt \cw{-H} \e{directory} or \cw{--html} \e{directory} |
257 | |
258 | \dd In this mode, \cw{agedu} will generate an HTML report of the |
259 | disk usage in the specified directory and its immediate |
260 | subdirectories, in the same form that it serves from its web server |
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261 | in \cw{-w} mode. |
262 | |
263 | \lcont{ |
264 | |
265 | By default, a single HTML report will be generated and simply |
266 | written to standard output, with no hyperlinks pointing to other |
267 | similar pages. If you also specify the \cw{-d} option (see below), |
268 | \cw{agedu} will instead write out a collection of HTML files with |
269 | hyperlinks between them, and call the top-level file |
270 | \cw{index.html}. |
271 | |
272 | } |
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273 | |
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274 | \dt \cw{--cgi} |
275 | |
276 | \dd In this mode, \cw{agedu} will run as the bulk of a CGI script |
277 | which provides the same set of web pages as the built-in web server |
278 | would. It will read the usual CGI environment variables, and write |
279 | CGI-style data to its standard output. |
280 | |
281 | \lcont{ |
282 | |
283 | The actual CGI program itself should be a tiny wrapper around |
284 | \cw{agedu} which passes it the \cw{--cgi} option, and also |
285 | (probably) \cw{-f} to locate the index file. \cw{agedu} will do |
286 | everything else. |
287 | |
288 | No access control is performed in this mode: restricting access to |
289 | CGI scripts is assumed to be the job of the web server. |
290 | |
291 | } |
292 | |
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293 | \U OPTIONS |
294 | |
295 | This section describes the various configuration options that affect |
296 | \cw{agedu}'s operation in one mode or another. |
297 | |
298 | The following option affects nearly all modes (except \cw{-S}): |
299 | |
300 | \dt \cw{-f} \e{filename} or \cw{--file} \e{filename} |
301 | |
302 | \dd Specifies the location of the index file which \cw{agedu} |
303 | creates, reads or removes depending on its operating mode. By |
304 | default, this is simply \cq{agedu.dat}, in whatever is the current |
305 | working directory when you run \cw{agedu}. |
306 | |
307 | The following options affect the disk-scanning modes, \cw{-s} and |
308 | \cw{-S}: |
309 | |
310 | \dt \cw{--cross-fs} and \cw{--no-cross-fs} |
311 | |
312 | \dd These configure whether or not the disk scan is permitted to |
313 | cross between different file systems. The default is not to: |
314 | \cw{agedu} will normally skip over subdirectories on which a |
315 | different file system is mounted. This makes it convenient when you |
316 | want to free up space on a particular file system which is running |
317 | low. However, in other circumstances you might wish to see general |
318 | information about the use of space no matter which file system it's |
319 | on (for instance, if your real concern is your backup media running |
320 | out of space, and if your backups do not treat different file |
321 | systems specially); in that situation, use \cw{--cross-fs}. |
322 | |
323 | \lcont{ |
324 | |
325 | (Note that this default is the opposite way round from the |
326 | corresponding option in \cw{du}.) |
327 | |
328 | } |
329 | |
330 | \dt \cw{--prune} \e{wildcard} and \cw{--prune-path} \e{wildcard} |
331 | |
332 | \dd These cause particular files or directories to be omitted |
333 | entirely from the scan. If \cw{agedu}'s scan encounters a file or |
334 | directory whose name matches the wildcard provided to the |
335 | \cw{--prune} option, it will not include that file in its index, and |
336 | also if it's a directory it will skip over it and not scan its |
337 | contents. |
338 | |
339 | \lcont{ |
340 | |
341 | Note that in most Unix shells, wildcards will probably need to be |
342 | escaped on the command line, to prevent the shell from expanding the |
343 | wildcard before \cw{agedu} sees it. |
344 | |
345 | \cw{--prune-path} is similar to \cw{--prune}, except that the |
346 | wildcard is matched against the entire pathname instead of just the |
347 | filename at the end of it. So whereas \cw{--prune *a*b*} will match |
348 | any file whose actual name contains an \cw{a} somewhere before a |
349 | \cw{b}, \cw{--prune-path *a*b*} will also match a file whose name |
350 | contains \cw{b} and which is inside a directory containing an |
351 | \cw{a}, or any file inside a directory of that form, and so on. |
352 | |
353 | } |
354 | |
355 | \dt \cw{--exclude} \e{wildcard} and \cw{--exclude-path} \e{wildcard} |
356 | |
357 | \dd These cause particular files or directories to be omitted from |
358 | the index, but not from the scan. If \cw{agedu}'s scan encounters a |
359 | file or directory whose name matches the wildcard provided to the |
360 | \cw{--exclude} option, it will not include that file in its index |
361 | \dash but unlike \cw{--prune}, if the file in question is a |
362 | directory it will still scan its contents and index them if they are |
363 | not ruled out themselves by \cw{--exclude} options. |
364 | |
365 | \lcont{ |
366 | |
367 | As above, \cw{--exclude-path} is similar to \cw{--exclude}, except |
368 | that the wildcard is matched against the entire pathname. |
369 | |
370 | } |
371 | |
372 | \dt \cw{--include} \e{wildcard} and \cw{--include-path} \e{wildcard} |
373 | |
374 | \dd These cause particular files or directories to be re-included in |
375 | the index and the scan, if they had previously been ruled out by one |
376 | of the above exclude or prune options. You can interleave include, |
377 | exclude and prune options as you wish on the command line, and if |
378 | more than one of them applies to a file then the last one takes |
379 | priority. |
380 | |
381 | \lcont{ |
382 | |
383 | For example, if you wanted to see only the disk space taken up by |
384 | MP3 files, you might run |
385 | |
386 | \c $ agedu -s . --exclude '*' --include '*.mp3' |
387 | \e bbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbb |
388 | |
389 | which will cause everything to be omitted from the scan, but then |
390 | the MP3 files to be put back in. If you then wanted only a subset of |
391 | those MP3s, you could then exclude some of them again by adding, |
392 | say, \cq{--exclude-path './queen/*'} (or, more efficiently, |
393 | \cq{--prune ./queen}) on the end of that command. |
394 | |
395 | As with the previous two options, \cw{--include-path} is similar to |
396 | \cw{--include} except that the wildcard is matched against the |
397 | entire pathname. |
398 | |
399 | } |
400 | |
401 | \dt \cw{--progress}, \cw{--no-progress} and \cw{--tty-progress} |
402 | |
403 | \dd When \cw{agedu} is scanning a directory tree, it will typically |
404 | print a one-line progress report every second showing where it has |
405 | reached in the scan, so you can have some idea of how much longer it |
406 | will take. (Of course, it can't predict \e{exactly} how long it will |
407 | take, since it doesn't know which of the directories it hasn't |
408 | scanned yet will turn out to be huge.) |
409 | |
410 | \lcont{ |
411 | |
412 | By default, those progress reports are displayed on \cw{agedu}'s |
413 | standard error channel, if that channel points to a terminal device. |
414 | If you need to manually enable or disable them, you can use the |
415 | above three options to do so: \cw{--progress} unconditionally |
416 | enables the progress reports, \cw{--no-progress} unconditionally |
417 | disables them, and \cw{--tty-progress} reverts to the default |
418 | behaviour which is conditional on standard error being a terminal. |
419 | |
420 | } |
421 | |
422 | \dt \cw{--dir-atime} and \cw{--no-dir-atime} |
423 | |
424 | \dd In normal operation, \cw{agedu} ignores the atimes (last access |
425 | times) on the \e{directories} it scans: it only pays attention to |
426 | the atimes of the \e{files} inside those directories. This is |
427 | because directory atimes tend to be reset by a lot of system |
428 | administrative tasks, such as \cw{cron} jobs which scan the file |
429 | system for one reason or another \dash or even other invocations of |
430 | \cw{agedu} itself, though it tries to avoid modifying any atimes if |
431 | possible. So the literal atimes on directories are typically not |
432 | representative of how long ago the data in question was last |
433 | accessed with real intent to use that data in particular. |
434 | |
435 | \lcont{ |
436 | |
437 | Instead, \cw{agedu} makes up a fake atime for every directory it |
438 | scans, which is equal to the newest atime of any file in or below |
439 | that directory (or the directory's last \e{modification} time, |
440 | whichever is newest). This is based on the assumption that all |
441 | \e{important} accesses to directories are actually accesses to the |
442 | files inside those directories, so that when any file is accessed |
443 | all the directories on the path leading to it should be considered |
444 | to have been accessed as well. |
445 | |
446 | In unusual cases it is possible that a directory itself might embody |
447 | important data which is accessed by reading the directory. In that |
448 | situation, \cw{agedu}'s atime-faking policy will misreport the |
449 | directory as disused. In the unlikely event that such directories |
450 | form a significant part of your disk space usage, you might want to |
451 | turn off the faking. The \cw{--dir-atime} option does this: it |
452 | causes the disk scan to read the original atimes of the directories |
453 | it scans. |
454 | |
455 | The faking of atimes on directories also requires a processing pass |
456 | over the index file after the main disk scan is complete. |
457 | \cw{--dir-atime} also turns this pass off. Hence, this option |
458 | affects the \cw{-L} option as well as \cw{-s} and \cw{-S}. |
459 | |
460 | (The previous section mentioned that there might be subtle |
461 | differences between the output of \cw{agedu -s /path -D} and |
462 | \cw{agedu -S /path}. This is why. Doing a scan with \cw{-s} and then |
463 | dumping it with \cw{-D} will dump the fully faked atimes on the |
464 | directories, whereas doing a scan-to-dump with \cw{-S} will dump |
465 | only \e{partially} faked atimes \dash specifically, each directory's |
466 | last modification time \dash since the subsequent processing pass |
467 | will not have had a chance to take place. However, loading either of |
468 | the resulting dump files with \cw{-L} will perform the atime-faking |
469 | processing pass, leading to the same data in the index file in each |
470 | case. In normal usage it should be safe to ignore all of this |
471 | complexity.) |
472 | |
473 | } |
474 | |
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475 | \dt \cw{--mtime} |
476 | |
477 | \dd This option causes \cw{agedu} to index files by their last |
478 | modification time instead of their last access time. You might want |
479 | to use this if your last access times were completely useless for |
480 | some reason: for example, if you had recently searched every file on |
481 | your system, the system would have lost all the information about |
482 | what files you hadn't recently accessed before then. Using this |
483 | option is liable to be less effective at finding genuinely wasted |
484 | space than the normal mode (that is, it will be more likely to flag |
485 | things as disused when they're not, so you will have more candidates |
486 | to go through by hand looking for data you don't need), but may be |
487 | better than nothing if your last-access times are unhelpful. |
488 | |
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489 | \lcont{ |
490 | |
491 | Another use for this mode might be to find \e{recently created} |
492 | large data. If your disk has been gradually filling up for years, |
493 | the default mode of \cw{agedu} will let you find unused data to |
494 | delete; but if you know your disk had plenty of space recently and |
495 | now it's suddenly full, and you suspect that some rogue program has |
496 | left a large core dump or output file, then \cw{agedu --mtime} might |
497 | be a convenient way to locate the culprit. |
498 | |
499 | } |
500 | |
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501 | The following option affects all the modes that generate reports: |
502 | the web server mode \cw{-w}, the stand-alone HTML generation mode |
503 | \cw{-H} and the text report mode \cw{-t}. |
504 | |
505 | \dt \cw{--files} |
506 | |
507 | \dd This option causes \cw{agedu}'s reports to list the individual |
508 | files in each directory, instead of just giving a combined report |
509 | for everything that's not in a subdirectory. |
510 | |
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511 | The following options affect the stand-alone HTML generation mode |
512 | \cw{-H} and the text report mode \cw{-t}. |
513 | |
514 | \dt \cw{-d} \e{depth} or \cw{--depth} \e{depth} |
515 | |
516 | \dd This option controls the maximum depth to which \cw{agedu} |
517 | recurses when generating a text or HTML report. |
518 | |
519 | \lcont{ |
520 | |
521 | In text mode, the default is 1, meaning that the report will include |
522 | the directory given on the command line and all of its immediate |
523 | subdirectories. A depth of two includes another level below that, |
524 | and so on; a depth of zero means \e{only} the directory on the |
525 | command line. |
526 | |
527 | In HTML mode, specifying this option switches \cw{agedu} from |
528 | writing out a single HTML file to writing out multiple files which |
529 | link to each other. A depth of 1 means \cw{agedu} will write out an |
530 | HTML file for the given directory and also one for each of its |
531 | immediate subdirectories. |
532 | |
533 | If you want \cw{agedu} to recurse as deeply as possible, give the |
534 | special word \cq{max} as an argument to \cw{-d}. |
535 | |
536 | } |
537 | |
538 | \dt \cw{-o} \e{filename} or \cw{--output} \e{filename} |
539 | |
540 | \dd This option is used to specify an output file for \cw{agedu} to |
541 | write its report to. In text mode or single-file HTML mode, the |
542 | argument is treated as the name of a file. In multiple-file HTML |
543 | mode, the argument is treated as the name of a directory: the |
544 | directory will be created if it does not already exist, and the |
545 | output HTML files will be created inside it. |
546 | |
67159944 |
547 | The following options affect the web server mode \cw{-w}, and in one |
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548 | case also the stand-alone HTML generation mode \cw{-H}: |
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549 | |
550 | \dt \cw{-r} \e{age range} or \cw{--age-range} \e{age range} |
551 | |
552 | \dd The HTML reports produced by \cw{agedu} use a range of colours |
553 | to indicate how long ago data was last accessed, running from red |
554 | (representing the most disused data) to green (representing the |
555 | newest). By default, the lengths of time represented by the two ends |
556 | of that spectrum are chosen by examining the data file to see what |
557 | range of ages appears in it. However, you might want to set your own |
558 | limits, and you can do this using \cw{-r}. |
559 | |
560 | \lcont{ |
561 | |
562 | The argument to \cw{-r} consists of a single age, or two ages |
563 | separated by a minus sign. An age is a number, followed by one of |
564 | \cq{y} (years), \cq{m} (months), \cq{w} (weeks) or \cq{d} (days). |
565 | The first age in the range represents the oldest data, and will be |
566 | coloured red in the HTML; the second age represents the newest, |
567 | coloured green. If the second age is not specified, it will default |
568 | to zero (so that green means data which has been accessed \e{just |
569 | now}). |
570 | |
571 | For example, \cw{-r 2y} will mark data in red if it has been unused |
572 | for two years or more, and green if it has been accessed just now. |
573 | \cw{-r 2y-3m} will similarly mark data red if it has been unused for |
574 | two years or more, but will mark it green if it has been accessed |
575 | three months ago or later. |
576 | |
577 | } |
578 | |
579 | \dt \cw{--address} \e{addr}[\cw{:}\e{port}] |
580 | |
581 | \dd Specifies the network address and port number on which |
582 | \cw{agedu} should listen when running its web server. If you want |
583 | \cw{agedu} to listen for connections coming in from any source, you |
584 | should probably specify the special IP address \cw{0.0.0.0}. If the |
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585 | port number is omitted, an arbitrary unused port will be chosen for |
586 | you and displayed. |
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587 | |
588 | \lcont{ |
589 | |
590 | If you specify this option, \cw{agedu} will not print its URL on |
591 | standard output (since you are expected to know what address you |
592 | told it to listen to). |
593 | |
594 | } |
595 | |
596 | \dt \cw{--auth} \e{auth-type} |
597 | |
598 | \dd Specifies how \cw{agedu} should control access to the web pages |
599 | it serves. The options are as follows: |
600 | |
601 | \lcont{ |
602 | |
603 | \dt \cw{magic} |
604 | |
605 | \dd This option only works on Linux, and only when the incoming |
606 | connection is from the same machine that \cw{agedu} is running on. |
607 | On Linux, the special file \cw{/proc/net/tcp} contains a list of |
608 | network connections currently known to the operating system kernel, |
609 | including which user id created them. So \cw{agedu} will look up |
610 | each incoming connection in that file, and allow access if it comes |
611 | from the same user id under which \cw{agedu} itself is running. |
612 | Therefore, in \cw{agedu}'s normal web server mode, you can safely |
613 | run it on a multi-user machine and no other user will be able to |
614 | read data out of your index file. |
615 | |
616 | \dt \cw{basic} |
617 | |
618 | \dd In this mode, \cw{agedu} will use HTTP Basic authentication: the |
619 | user will have to provide a username and password via their browser. |
620 | \cw{agedu} will normally make up a username and password for the |
621 | purpose, but you can specify your own; see below. |
622 | |
623 | \dt \cw{none} |
624 | |
625 | \dd In this mode, the web server is unauthenticated: anyone |
626 | connecting to it has full access to the reports generated by |
627 | \cw{agedu}. Do not do this unless there is nothing confidential at |
628 | all in your index file, or unless you are certain that nobody but |
629 | you can run processes on your computer. |
630 | |
631 | \dt \cw{default} |
632 | |
633 | \dd This is the default mode if you do not specify one of the above. |
634 | In this mode, \cw{agedu} will attempt to use Linux magic |
635 | authentication, but if it detects at startup time that |
636 | \cw{/proc/net/tcp} is absent or non-functional then it will fall |
637 | back to using HTTP Basic authentication and invent a user name and |
638 | password. |
639 | |
640 | } |
641 | |
642 | \dt \cw{--auth-file} \e{filename} or \cw{--auth-fd} \e{fd} |
643 | |
644 | \dd When \cw{agedu} is using HTTP Basic authentication, these |
645 | options allow you to specify your own user name and password. If you |
646 | specify \cw{--auth-file}, these will be read from the specified |
647 | file; if you specify \cw{--auth-fd} they will instead be read from a |
648 | given file descriptor which you should have arranged to pass to |
649 | \cw{agedu}. In either case, the authentication details should |
650 | consist of the username, followed by a colon, followed by the |
651 | password, followed \e{immediately} by end of file (no trailing |
652 | newline, or else it will be considered part of the password). |
653 | |
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654 | \dt \cw{--no-eof} |
655 | |
656 | \dd Stop \cw{agedu} in web server mode from looking for end-of-file on |
657 | standard input and treating it as a signal to terminate. |
658 | |
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659 | \U LIMITATIONS |
660 | |
661 | The data file is pretty large. The core of \cw{agedu} is the |
662 | tree-based data structure it uses in its index in order to |
663 | efficiently perform the queries it needs; this data structure |
664 | requires \cw{O(N log N)} storage. This is larger than you might |
665 | expect; a scan of my own home directory, containing half a million |
666 | files and directories and about 20Gb of data, produced an index file |
522edd92 |
667 | over 60Mb in size. Furthermore, since the data file must be |
668 | memory-mapped during most processing, it can never grow larger than |
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669 | available address space, so a \e{really} big filesystem may need to |
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670 | be indexed on a 64-bit computer. (This is one reason for the |
671 | existence of the \cw{-D} and \cw{-L} options: you can do the |
672 | scanning on the machine with access to the filesystem, and the |
673 | indexing on a machine big enough to handle it.) |
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674 | |
67159944 |
675 | The data structure also does not usefully permit access control |
676 | within the data file, so it would be difficult \dash even given the |
677 | willingness to do additional coding \dash to run a system-wide |
678 | \cw{agedu} scan on a \cw{cron} job and serve the right subset of |
679 | reports to each user. |
680 | |
fe8eebd4 |
681 | In certain circumstances, \cw{agedu} can report false positives |
682 | (reporting files as disused which are in fact in use) as well as the |
683 | more benign false negatives (reporting files as in use which are |
684 | not). This arises when a file is, semantically speaking, \q{read} |
685 | without actually being physically \e{read}. Typically this occurs |
686 | when a program checks whether the file's mtime has changed and only |
687 | bothers re-reading it if it has; programs which do this include |
688 | \cw{rsync}(\e{1}) and \cw{make}(\e{1}). Such programs will fail to |
689 | update the atime of unmodified files despite depending on their |
690 | continued existence; a directory full of such files will be reported |
691 | as disused by \cw{agedu} but deleting them will cause trouble. |
692 | |
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693 | \U LICENCE |
694 | |
695 | \cw{agedu} is free software, distributed under the MIT licence. Type |
696 | \cw{agedu --licence} to see the full licence text. |
697 | |
698 | \versionid $Id$ |