Estimating Linux's Size
Although their values are not used in estimating effort, I also counted the number of files; summaries of these values are included in appendix B.
Since the Linux kernel was the largest single component, and I had questions about the various inconsistencies in the ``Halloween'' documents, I made additional measures of the Linux kernel.
Some have objected because the counting approach used here includes lines not compiled into code in this Linux distribution. However, the primary objective of these measures was to estimate total effort to develop all of these components. Even if some lines are not normally enabled on Linux, it still required effort to develop that code. Code for other architectures still has value, for example, because it enables users to port to other architectures while using the component. Even if that code is no longer being maintained (e.g., because the architecture has become less popular), nevertheless someone had to invest effort to create it, the results benefitted someone, and if it is needed again it's still there (at least for use as a starting point). Code that is only enabled by compile-time options still has value, because if the options were desired the user could enable them and recompile. Code that is only used for testing still has value, because its use improves the quality of the software directly run by users. It is possible that there is some ``dead code'' (code that cannot be run under any circumstance), but it is expected that this amount of code is very small and would not signficantly affect the results. Andi Kleen (of SuSE) noted that if you wanted to only count compiled and running code, one technique (for some languages) would be to use gcc's ``-g'' option and use the resulting .stabs debugging information with some filtering (to exclude duplicated inline functions). I determined this to be out-of-scope for this paper, but this approach could be used to make additional measurements of the system.
A.4 Estimating Effort and Costs
For each build directory, I totalled the source lines of code (SLOC) for each language, then totalled those values to determine the SLOC for each directory. I then used the basic Constructive Cost Model (COCOMO) to estimate effort. The basic model is the simplest (and least accurate) model, but I simply did not have the additional information necessary to use the more complex (and more accurate) models. COCOMO is described in depth by Boehm [1981].Basic COCOMO is designed to estimate the time from product design (after plans and requirements have been developed) through detailed design, code, unit test, and integration testing. Note that plans and requirement development are not included. COCOMO is designed to include management overhead and the creation of documentation (e.g., user manuals) as well as the code itself. Again, see Boehm [1981] for a more detailed description of the model's assumptions.
In the basic COCOMO model, estimated man-months of effort, design through test, equals 2.4*(KSLOC)^1.05, where KSLOC is the total physical SLOC divided by 1000.
I assumed that each package was built completely independently and that there were no efforts necessary for integration not represented in the code itself. This almost certainly underestimates the true costs, but for most packages it's actually true (many packages don't interact with each other at all). I wished to underestimate (instead of overestimate) the effort and costs, and having no better model, I assumed the simplest possible integration effort. This meant that I applied the model to each component, then summed the results, as opposed to applying the model once to the grand total of all software.
Note that the only input to this model is source lines of code, so some factors simply aren't captured. For example, creating some kinds of data (such as fonts) can be very time-consuming, but this isn't directly captured by this model. Some programs are intentionally designed to be data-driven, that is, they're designed as small programs which are driven by specialized data. Again, this data may be as complex to develop as code, but this is not counted.
Another example of uncaptured factors is the difficulty of writing kernel code. It's generally acknowledged that writing kernel-level code is more difficult than most other kinds of code, because this kind of code is subject to a subtle timing and race conditions, hardware interactions, a small stack, and none of the normal error protections. In this paper I do not attempt to account for this. You could try to use the Intermediate COCOMO model to try to account for this, but again this requires knowledge of other factors that can only be guessed at. Again, the effort estimation probably significantly underestimates the actual effort represented here.
It's worth noting that there is an update to COCOMO, COCOMO II. However, COCOMO II requires as its input logical (not physical) SLOC, and since this measure is much harder to obtain, I did not pursue it for this paper. More information about COCOMO II is available at the web site http://sunset.usc.edu/research/COCOMOII/index.html. A nice overview paper where you can learn more about software metrics is Masse [1997].
I assumed that an average U.S. programmer/analyst salary in the year 2000 was $56,286 per year; this value was from the ComputerWorld, September 4, 2000's Salary Survey, Overhead is much harder to estimate; I did not find a definitive source for information on overheads. After informal discussions with several cost analysts, I determined that an overhead of 2.4 would be representative of the overhead sustained by a typical software development company. Should you diagree with these figures, I've provided all the information necessary to recalculate your own cost figures; just start with the effort estimates and recalculate cost yourself.
Appendix B. More Detailed Results
This appendix provides some more detailed results. B.1 lists the SLOC found in each build directory; B.2 shows counts of files for each category of file; B.3 presents some additional measures about the Linux kernel. B.4 presents some SLOC totals of putatively ``minimal'' systems. You can learn more at http://www.dwheeler.com/sloc.B.1 SLOC in Build Directories The following is a list of all build directories, and the source lines of code (SLOC) found in them, followed by a few statistics counting files (instead of SLOC).
Remember that duplicate files are only counted once, with the build directory ``first in ASCII sort order'' receiving any duplicates (to break ties). As a result, some build directories have a smaller number than might at first make sense. For example, the ``kudzu'' build directory does contain code, but all of it is also contained in the ``Xconfigurator'' build directory.. and since that directory sorts first, the kudzu package is considered to have ``no code''.
The columns are SLOC (total physical source lines of code), Directory (the name of the build directory, usually the same or similar to the package name), and SLOC-by-Language (Sorted). This last column lists languages by name and the number of SLOC in that language; zeros are not shown, and the list is sorted from largest to smallest in that build directory. Similarly, the directories are sorted from largest to smallest total SLOC.
SLOC Directory SLOC-by-Language (Sorted)
1526722 linux ansic=1462165,asm=59574,sh=2860,perl=950,tcl=414,
yacc=324,lex=230,awk=133,sed=72
1291745 XFree86-3.3.6 ansic=1246420,asm=14913,sh=13433,tcl=8362,cpp=4358,
yacc=2710,perl=711,awk=393,lex=383,sed=57,csh=5
720112 egcs-1.1.2 ansic=598682,cpp=75206,sh=14307,asm=11462,yacc=7988,
lisp=7252,exp=2887,fortran=1515,objc=482,sed=313,perl=18
652087 gdb-19991004 ansic=587542,exp=37737,sh=9630,cpp=6735,asm=4139,
yacc=4117,lisp=1820,sed=220,awk=142,fortran=5
625073 emacs-20.5 lisp=453647,ansic=169624,perl=884,sh=652,asm=253,
csh=9,sed=4
467120 binutils-2.9.5.0.22 ansic=407352,asm=27575,exp=12265,sh=7398,yacc=5606,
cpp=4454,lex=1479,sed=557,lisp=394,awk=24,perl=16
415026 glibc-2.1.3 ansic=378753,asm=30644,sh=2520,cpp=1704,awk=910,
perl=464,sed=16,csh=15
327021 tcltk-8.0.5 ansic=240093,tcl=71947,sh=8531,exp=5150,yacc=762,
awk=273,perl=265
247026 postgresql-6.5.3 ansic=207735,yacc=10718,java=8835,tcl=7709,sh=7399,
lex=1642,perl=1206,python=959,cpp=746,asm=70,csh=5,sed=2
235702 gimp-1.0.4 ansic=225211,lisp=8497,sh=1994
231072 Mesa ansic=195796,cpp=17717,asm=13467,sh=4092
222220 krb5-1.1.1 ansic=192822,exp=19364,sh=4829,yacc=2476,perl=1528,
awk=393,python=348,lex=190,csh=147,sed=123
206237 perl5.005_03 perl=94712,ansic=89366,sh=15654,lisp=5584,yacc=921
205082 qt-2.1.0-beta1 cpp=180866,ansic=20513,yacc=2284,sh=538,lex=464,
perl=417
200628 Python-1.5.2 python=100935,ansic=96323,lisp=2353,sh=673,perl=342,
sed=2
199982 gs5.50 ansic=195491,cpp=2266,asm=968,sh=751,lisp=405,perl=101
193916 teTeX-1.0 ansic=166041,sh=10263,cpp=9407,perl=3795,pascal=1546,
yacc=1507,awk=522,lex=323,sed=297,asm=139,csh=47,lisp=29
155035 bind-8.2.2_P5 ansic=131946,sh=10068,perl=7607,yacc=2231,cpp=1360,
csh=848,awk=753,lex=222
140130 AfterStep-APPS-20000124 ansic=135806,sh=3340,cpp=741,perl=243
138931 kdebase cpp=113971,ansic=23016,perl=1326,sh=618
138118 gtk+-1.2.6 ansic=137006,perl=479,sh=352,awk=274,lisp=7
138024 gated-3-5-11 ansic=126846,yacc=7799,sh=1554,lex=877,awk=666,csh=235,
sed=35,lisp=12
133193 kaffe-1.0.5 java=65275,ansic=62125,cpp=3923,perl=972,sh=814,
asm=84
131372 jade-1.2.1 cpp=120611,ansic=8228,sh=2150,perl=378,sed=5
128672 gnome-libs-1.0.55 ansic=125373,sh=2178,perl=667,awk=277,lisp=177
127536 pine4.21 ansic=126678,sh=766,csh=62,perl=30
121878 ImageMagick-4.2.9 ansic=99383,sh=11143,cpp=8870,perl=2024,tcl=458
119613 lynx2-8-3 ansic=117385,sh=1860,perl=340,csh=28
116951 mc-4.5.42 ansic=114406,sh=1996,perl=345,awk=148,csh=56
116615 gnumeric-0.48 ansic=115592,yacc=600,lisp=191,sh=142,perl=67,python=23
113272 xlispstat-3-52-17 ansic=91484,lisp=21769,sh=18,csh=1
113241 vim-5.6 ansic=111724,awk=683,sh=469,perl=359,csh=6
109824 php-3.0.15 ansic=105901,yacc=1887,sh=1381,perl=537,awk=90,cpp=28
104032 linuxconf-1.17r2 cpp=93139,perl=4570,sh=2984,java=2741,ansic=598
102674 libgr-2.0.13 ansic=99647,sh=2438,csh=589
100951 lam-6.3.1 ansic=86177,cpp=10569,sh=3677,perl=322,fortran=187,
csh=19
99066 krb4-1.0 ansic=84077,asm=5163,cpp=3775,perl=2508,sh=1765,
yacc=1509,lex=236,awk=33
94637 xlockmore-4.15 ansic=89816,cpp=1987,tcl=1541,sh=859,java=285,perl=149
93940 kdenetwork cpp=80075,ansic=7422,perl=6260,sh=134,tcl=49
92964 samba-2.0.6 ansic=88308,sh=3557,perl=831,awk=158,csh=110
91213 anaconda-6.2.2 ansic=74303,python=13657,sh=1583,yacc=810,lex=732,
perl=128
89959 xscreensaver-3.23 ansic=88488,perl=1070,sh=401
88128 cvs-1.10.7 ansic=68303,sh=17909,perl=902,yacc=826,csh=181,lisp=7
87940 isdn4k-utils ansic=78752,perl=3369,sh=3089,cpp=2708,tcl=22
85383 xpdf-0.90 cpp=60427,ansic=21400,sh=3556
81719 inn-2.2.2 ansic=62403,perl=10485,sh=5465,awk=1567,yacc=1547,
lex=249,tcl=3
80343 kdelibs cpp=71217,perl=5075,ansic=3660,yacc=240,lex=116,
sh=35
79997 WindowMaker-0.61.1 ansic=77924,sh=1483,perl=371,lisp=219
78787 extace-1.2.15 ansic=66571,sh=9322,perl=2894
77873 apache_1.3.12 ansic=69191,sh=6781,perl=1846,cpp=55
75257 xpilot-4.1.0 ansic=68669,tcl=3479,cpp=1896,sh=1145,perl=68
73817 w3c-libwww-5.2.8 ansic=64754,sh=4678,cpp=3181,perl=1204
72726 ucd-snmp-4.1.1 ansic=64411,perl=5558,sh=2757
72425 gnome-core-1.0.55 ansic=72230,perl=141,sh=54
71810 jikes cpp=71452,java=358
70260 groff-1.15 cpp=59453,ansic=5276,yacc=2957,asm=1866,perl=397,
sh=265,sed=46
69265 fvwm-2.2.4 ansic=63496,cpp=2463,perl=1835,sh=723,yacc=596,lex=152
69246 linux-86 ansic=63328,asm=5276,sh=642
68997 blt2.4g ansic=58630,tcl=10215,sh=152
68884 squid-2.3.STABLE1 ansic=66305,sh=1570,perl=1009
68560 bash-2.03 ansic=56758,sh=7264,yacc=2808,perl=1730
68453 kdegraphics cpp=34208,ansic=29347,sh=4898
65722 xntp3-5.93 ansic=60190,perl=3633,sh=1445,awk=417,asm=37
62922 ppp-2.3.11 ansic=61756,sh=996,exp=82,perl=44,csh=44
62137 sgml-tools-1.0.9 cpp=38543,ansic=19185,perl=2866,lex=560,sh=532,
lisp=309,awk=142
61688 imap-4.7 ansic=61628,sh=60
61324 ncurses-5.0 ansic=45856,ada=8217,cpp=3720,sh=2822,awk=506,perl=103,
sed=100
60429 kdesupport ansic=42421,cpp=17810,sh=173,awk=13,csh=12
60302 openldap-1.2.9 ansic=58078,sh=1393,perl=630,python=201
57217 xfig.3.2.3-beta-1 ansic=57212,csh=5
56093 lsof_4.47 ansic=50268,sh=4753,perl=856,awk=214,asm=2
55667 uucp-1.06.1 ansic=52078,sh=3400,perl=189
54935 gnupg-1.0.1 ansic=48884,asm=4586,sh=1465
54603 glade-0.5.5 ansic=49545,sh=5058
54431 svgalib-1.4.1 ansic=53725,asm=630,perl=54,sh=22
53141 AfterStep-1.8.0 ansic=50898,perl=1168,sh=842,cpp=233
52808 kdeutils cpp=41365,ansic=9693,sh=1434,awk=311,sed=5
52574 nmh-1.0.3 ansic=50698,sh=1785,awk=74,sed=17
51813 freetype-1.3.1 ansic=48929,sh=2467,cpp=351,csh=53,perl=13
51592 enlightenment-0.15.5 ansic=51569,sh=23
50970 cdrecord-1.8 ansic=48595,sh=2177,perl=194,sed=4
49370 tin-1.4.2 ansic=47763,sh=908,yacc=699
49325 imlib-1.9.7 ansic=49260,sh=65
48223 kdemultimedia ansic=24248,cpp=22275,tcl=1004,sh=621,perl=73,awk=2
47067 bash-1.14.7 ansic=41654,sh=3140,yacc=2197,asm=48,awk=28
46312 tcsh-6.09.00 ansic=43544,sh=921,lisp=669,perl=593,csh=585
46159 unzip-5.40 ansic=40977,cpp=3778,asm=1271,sh=133
45811 mutt-1.0.1 ansic=45574,sh=237
45589 am-utils-6.0.3 ansic=33389,sh=8950,perl=2421,lex=454,yacc=375
45485 guile-1.3 ansic=38823,lisp=4626,asm=1514,sh=310,awk=162,csh=50
45378 gnuplot-3.7.1 ansic=43276,lisp=661,asm=539,objc=387,csh=297,perl=138,
sh=80
44323 mgetty-1.1.21 ansic=33757,perl=5889,sh=3638,tcl=756,lisp=283
42880 sendmail-8.9.3 ansic=40364,perl=1737,sh=779
42746 elm2.5.3 ansic=32931,sh=9774,awk=41
41388 p2c-1.22 ansic=38788,pascal=2499,perl=101
41205 gnome-games-1.0.51 ansic=31191,lisp=6966,cpp=3048
39861 rpm-3.0.4 ansic=36994,sh=1505,perl=1355,python=7
39160 util-linux-2.10f ansic=38627,sh=351,perl=65,csh=62,sed=55
38927 xmms-1.0.1 ansic=38366,asm=398,sh=163
38548 ORBit-0.5.0 ansic=35656,yacc=1750,sh=776,lex=366
38453 zsh-3.0.7 ansic=36208,sh=1763,perl=331,awk=145,sed=6
37515 ircii-4.4 ansic=36647,sh=852,lex=16
37360 tiff-v3.5.4 ansic=32734,sh=4054,cpp=572
36338 textutils-2.0a ansic=18949,sh=16111,perl=1218,sed=60
36243 exmh-2.1.1 tcl=35844,perl=316,sh=49,exp=34
36239 x11amp-0.9-alpha3 ansic=31686,sh=4200,asm=353
35812 xloadimage.4.1 ansic=35705,sh=107
35554 zip-2.3 ansic=32108,asm=3446
35397 gtk-engines-0.10 ansic=20636,sh=14761
35136 php-2.0.1 ansic=33991,sh=1056,awk=89
34882 pmake ansic=34599,sh=184,awk=58,sed=41
34772 xpuzzles-5.4.1 ansic=34772
34768 fileutils-4.0p ansic=31324,sh=2042,yacc=841,perl=561
33203 strace-4.2 ansic=30891,sh=1988,perl=280,lisp=44
32767 trn-3.6 ansic=25264,sh=6843,yacc=660
32277 pilot-link.0.9.3 ansic=26513,java=2162,cpp=1689,perl=971,yacc=660,
python=268,tcl=14
31994 korganizer cpp=23402,ansic=5884,yacc=2271,perl=375,lex=61,sh=1
31174 ncftp-3.0beta21 ansic=30347,cpp=595,sh=232
30438 gnome-pim-1.0.55 ansic=28665,yacc=1773
30122 scheme-3.2 lisp=19483,ansic=10515,sh=124
30061 tcpdump-3.4 ansic=29208,yacc=236,sh=211,lex=206,awk=184,csh=16
29730 screen-3.9.5 ansic=28156,sh=1574
29315 jed ansic=29315
29091 xchat-1.4.0 ansic=28894,perl=121,python=53,sh=23
28897 ncpfs-2.2.0.17 ansic=28689,sh=182,tcl=26
28449 slrn-0.9.6.2 ansic=28438,sh=11
28261 xfishtank-2.1tp ansic=28261
28186 texinfo-4.0 ansic=26404,sh=841,awk=451,perl=256,lisp=213,sed=21
28169 e2fsprogs-1.18 ansic=27250,awk=437,sh=339,sed=121,perl=22
28118 slang ansic=28118
27860 kdegames cpp=27507,ansic=340,sh=13
27117 librep-0.10 ansic=19381,lisp=5385,sh=2351
27040 mikmod-3.1.6 ansic=26975,sh=55,awk=10
27022 x3270-3.1.1 ansic=26456,sh=478,exp=88
26673 lout-3.17 ansic=26673
26608 Xaw3d-1.3 ansic=26235,yacc=247,lex=126
26363 gawk-3.0.4 ansic=19871,awk=2519,yacc=2046,sh=1927
26146 libxml-1.8.6 ansic=26069,sh=77
25994 xrn-9.02 ansic=24686,yacc=888,sh=249,lex=92,perl=35,awk=31,
csh=13
25915 gv-3.5.8 ansic=25821,sh=94
25479 xpaint ansic=25456,sh=23
25236 shadow-19990827 ansic=23464,sh=883,yacc=856,perl=33
24910 kdeadmin cpp=19919,sh=3936,perl=1055
24773 pdksh-5.2.14 ansic=23599,perl=945,sh=189,sed=40
24583 gmp-2.0.2 ansic=17888,asm=5252,sh=1443
24387 mars_nwe ansic=24158,sh=229
24270 gnome-python-1.0.51 python=14331,ansic=9791,sh=148
23838 kterm-6.2.0 ansic=23838
23666 enscript-1.6.1 ansic=22365,lex=429,perl=308,sh=291,yacc=164,lisp=109
22373 sawmill-0.24 ansic=11038,lisp=8172,sh=3163
22279 make-3.78.1 ansic=19287,sh=2029,perl=963
22011 libpng-1.0.5 ansic=22011
21593 xboard-4.0.5 ansic=20640,lex=904,sh=41,csh=5,sed=3
21010 netkit-telnet-0.16 ansic=14796,cpp=6214
20433 pam-0.72 ansic=18936,yacc=634,sh=482,perl=321,lex=60
20125 ical-2.2 cpp=12651,tcl=6763,sh=624,perl=60,ansic=27
20078 gd1.3 ansic=19946,perl=132
19971 wu-ftpd-2.6.0 ansic=17572,yacc=1774,sh=421,perl=204
19500 gnome-utils-1.0.50 ansic=18099,yacc=824,lisp=577
19065 joe ansic=18841,asm=224
18885 X11R6-contrib-3.3.2 ansic=18616,lex=161,yacc=97,sh=11
18835 glib-1.2.6 ansic=18702,sh=133
18151 git-4.3.19 ansic=16166,sh=1985
18020 xboing ansic=18006,sh=14
17939 sh-utils-2.0 ansic=13366,sh=3027,yacc=871,perl=675
17765 mtools-3.9.6 ansic=16155,sh=1602,sed=8
17750 gettext-0.10.35 ansic=13414,lisp=2030,sh=1983,yacc=261,perl=53,sed=9
17682 bc-1.05 ansic=9186,sh=7236,yacc=967,lex=293
17271 fetchmail-5.3.1 ansic=13441,python=1490,sh=1246,yacc=411,perl=321,
lex=238,awk=124
17259 sox-12.16 ansic=16659,sh=600
16785 control-center-1.0.51 ansic=16659,sh=126
16266 dhcp-2.0 ansic=15328,sh=938
15967 SVGATextMode-1.9-src ansic=15079,yacc=340,sh=294,lex=227,sed=15,
asm=12
15868 kpilot-3.1b9 cpp=8613,ansic=5640,yacc=1615
15851 taper-6.9a ansic=15851
15819 mpg123-0.59r ansic=14900,asm=919
15691 transfig.3.2.1 ansic=15643,sh=38,csh=10
15638 mod_perl-1.21 perl=10278,ansic=5124,sh=236
15522 console-tools-0.3.3 ansic=13335,yacc=986,sh=800,lex=291,perl=110
15456 rpm2html-1.2 ansic=15334,perl=122
15143 gnotepad+-1.1.4 ansic=15143
15108 GXedit1.23 ansic=15019,sh=89
15087 mm2.7 ansic=8044,csh=6924,sh=119
14941 readline-2.2.1 ansic=11375,sh=1890,perl=1676
14912 ispell-3.1 ansic=8380,lisp=3372,yacc=1712,cpp=585,objc=385,
csh=221,sh=157,perl=85,sed=15
14871 gnuchess-4.0.pl80 ansic=14584,sh=258,csh=29
14774 flex-2.5.4 ansic=13011,lex=1045,yacc=605,awk=72,sh=29,sed=12
14587 multimedia ansic=14577,sh=10
14516 libgtop-1.0.6 ansic=13768,perl=653,sh=64,asm=31
14427 mawk-1.2.2 ansic=12714,yacc=994,awk=629,sh=90
14363 automake-1.4 perl=10622,sh=3337,ansic=404
14350 rsync-2.4.1 ansic=13986,perl=179,sh=126,awk=59
14299 nfs-utils-0.1.6 ansic=14107,sh=165,perl=27
14269 rcs-5.7 ansic=12209,sh=2060
14255 tar-1.13.17 ansic=13014,lisp=592,sh=538,perl=111
14105 wmakerconf-2.1 ansic=13620,perl=348,sh=137
14039 less-346 ansic=14032,awk=7
13779 rxvt-2.6.1 ansic=13779
13586 wget-1.5.3 ansic=13509,perl=54,sh=23
13504 rp3-1.0.7 cpp=10416,ansic=2957,sh=131
13241 iproute2 ansic=12139,sh=1002,perl=100
13100 silo-0.9.8 ansic=10485,asm=2615
12657 macutils ansic=12657
12639 libungif-4.1.0 ansic=12381,sh=204,perl=54
12633 minicom-1.83.0 ansic=12503,sh=130
12593 audiofile-0.1.9 sh=6440,ansic=6153
12463 gnome-objc-1.0.2 objc=12365,sh=86,ansic=12
12313 jpeg-6a ansic=12313
12124 ypserv-1.3.9 ansic=11622,sh=460,perl=42
11790 lrzsz-0.12.20 ansic=9512,sh=1263,exp=1015
11775 modutils-2.3.9 ansic=9309,sh=1620,lex=484,yacc=362
11721 enlightenment-conf-0.15 ansic=6232,sh=5489
11633 net-tools-1.54 ansic=11531,sh=102
11404 findutils-4.1 ansic=11160,sh=173,exp=71
11299 xmorph-1999dec12 ansic=10783,tcl=516
10958 kpackage-1.3.10 cpp=8863,sh=1852,ansic=124,perl=119
10914 diffutils-2.7 ansic=10914
10404 gnorpm-0.9 ansic=10404
10271 gqview-0.7.0 ansic=10271
10267 libPropList-0.9.1 sh=5974,ansic=3982,lex=172,yacc=139
10187 dump-0.4b15 ansic=9422,sh=760,sed=5
10088 piranha ansic=10048,sh=40
10013 grep-2.4 ansic=9852,sh=103,awk=49,sed=9
9961 procps-2.0.6 ansic=9959,sh=2
9942 xpat2-1.04 ansic=9942
9927 procmail-3.14 ansic=8090,sh=1837
9873 nss_ldap-105 ansic=9784,perl=89
9801 man-1.5h1 ansic=7377,sh=1802,perl=317,awk=305
9741 Xconfigurator-4.3.5 ansic=9578,perl=125,sh=32,python=6
9731 ld.so-1.9.5 ansic=6960,asm=2401,sh=370
9725 gpm-1.18.1 ansic=8107,yacc=1108,lisp=221,sh=209,awk=74,sed=6
9699 bison-1.28 ansic=9650,sh=49
9666 ash-linux-0.2 ansic=9445,sh=221
9607 cproto-4.6 ansic=7600,lex=985,yacc=761,sh=261
9551 pwdb-0.61 ansic=9488,sh=63
9465 rdist-6.1.5 ansic=8306,sh=553,yacc=489,perl=117
9263 ctags-3.4 ansic=9240,sh=23
9138 gftp-2.0.6a ansic=9138
8939 mkisofs-1.12b5 ansic=8939
8766 pxe-linux cpp=4463,ansic=3622,asm=681
8572 psgml-1.2.1 lisp=8572
8540 xxgdb-1.12 ansic=8540
8491 gtop-1.0.5 ansic=8151,cpp=340
8356 gedit-0.6.1 ansic=8225,sh=131
8303 dip-3.3.7o ansic=8207,sh=96
7859 libglade-0.11 ansic=5898,sh=1809,python=152
7826 xpm-3.4k ansic=7750,sh=39,cpp=37
7740 sed-3.02 ansic=7301,sed=359,sh=80
7617 cpio-2.4.2 ansic=7598,sh=19
7615 esound-0.2.17 ansic=7387,sh=142,csh=86
7570 sharutils-4.2.1 ansic=5511,perl=1741,sh=318
7427 ed-0.2 ansic=7263,sh=164
7255 lilo ansic=3522,asm=2557,sh=740,perl=433,cpp=3
7227 cdparanoia-III-alpha9.6 ansic=6006,sh=1221
7095 xgammon-0.98 ansic=6506,lex=589
7041 newt-0.50.8 ansic=6526,python=515
7030 ee-0.3.11 ansic=7007,sh=23
6976 aboot-0.5 ansic=6680,asm=296
6968 mailx-8.1.1 ansic=6963,sh=5
6877 lpr ansic=6842,sh=35
6827 gnome-media-1.0.51 ansic=6827
6646 iputils ansic=6646
6611 patch-2.5 ansic=6561,sed=50
6592 xosview-1.7.1 cpp=6205,ansic=367,awk=20
6550 byacc-1.9 ansic=5520,yacc=1030
6496 pidentd-3.0.10 ansic=6475,sh=21
6391 m4-1.4 ansic=5993,lisp=243,sh=155
6306 gzip-1.2.4a ansic=5813,asm=458,sh=24,perl=11
6234 awesfx-0.4.3a ansic=6234
6172 sash-3.4 ansic=6172
6116 lslk ansic=5325,sh=791
6090 joystick-1.2.15 ansic=6086,sh=4
6072 kdoc perl=6010,sh=45,cpp=17
6043 irda-utils-0.9.10 ansic=5697,sh=263,perl=83
6033 sysvinit-2.78 ansic=5256,sh=777
6025 pnm2ppa ansic=5708,sh=317
6021 rpmfind-1.4 ansic=6021
5981 indent-2.2.5 ansic=5958,sh=23
5975 ytalk-3.1 ansic=5975
5960 isapnptools-1.21 ansic=4394,yacc=1383,perl=123,sh=60
5744 gdm-2.0beta2 ansic=5632,sh=112
5594 isdn-config cpp=3058,sh=2228,perl=308
5526 efax-0.9 ansic=4570,sh=956
5383 acct-6.3.2 ansic=5016,cpp=287,sh=80
5115 libtool-1.3.4 sh=3374,ansic=1741
5111 netkit-ftp-0.16 ansic=5111
4996 bzip2-0.9.5d ansic=4996
4895 xcpustate-2.5 ansic=4895
4792 libelf-0.6.4 ansic=3310,sh=1482
4780 make-3.78.1_pvm-0.5 ansic=4780
4542 gpgp-0.4 ansic=4441,sh=101
4430 gperf-2.7 cpp=2947,exp=745,ansic=695,sh=43
4367 aumix-1.30.1 ansic=4095,sh=179,sed=93
4087 zlib-1.1.3 ansic=2815,asm=712,cpp=560
4038 sysklogd-1.3-31 ansic=3741,perl=158,sh=139
4024 rep-gtk-0.8 ansic=2905,lisp=971,sh=148
3962 netkit-timed-0.16 ansic=3962
3929 initscripts-5.00 sh=2035,ansic=1866,csh=28
3896 ltrace-0.3.10 ansic=2986,sh=854,awk=56
3885 phhttpd-0.1.0 ansic=3859,sh=26
3860 xdaliclock-2.18 ansic=3837,sh=23
3855 pciutils-2.1.5 ansic=3800,sh=55
3804 quota-2.00-pre3 ansic=3795,sh=9
3675 dosfstools-2.2 ansic=3675
3654 tcp_wrappers_7.6 ansic=3654
3651 ipchains-1.3.9 ansic=2767,sh=884
3625 autofs-3.1.4 ansic=2862,sh=763
3588 netkit-rsh-0.16 ansic=3588
3438 yp-tools-2.4 ansic=3415,sh=23
3433 dialog-0.6 ansic=2834,perl=349,sh=250
3415 ext2ed-0.1 ansic=3415
3315 gdbm-1.8.0 ansic=3290,cpp=25
3245 ypbind-3.3 ansic=1793,sh=1452
3219 playmidi-2.4 ansic=3217,sed=2
3096 xtrojka123 ansic=3087,sh=9
3084 at-3.1.7 ansic=1442,sh=1196,yacc=362,lex=84
3051 dhcpcd-1.3.18-pl3 ansic=2771,sh=280
3012 apmd ansic=2617,sh=395
2883 netkit-base-0.16 ansic=2883
2879 vixie-cron-3.0.1 ansic=2866,sh=13
2835 gkermit-1.0 ansic=2835
2810 kdetoys cpp=2618,ansic=192
2791 xjewel-1.6 ansic=2791
2773 mpage-2.4 ansic=2704,sh=69
2758 autoconf-2.13 sh=2226,perl=283,exp=167,ansic=82
2705 autorun-2.61 sh=1985,cpp=720
2661 cdp-0.33 ansic=2661
2647 file-3.28 ansic=2601,perl=46
2645 libghttp-1.0.4 ansic=2645
2631 getty_ps-2.0.7j ansic=2631
2597 pythonlib-1.23 python=2597
2580 magicdev-0.2.7 ansic=2580
2531 gnome-kerberos-0.2 ansic=2531
2490 sndconfig-0.43 ansic=2490
2486 bug-buddy-0.7 ansic=2486
2459 usermode-1.20 ansic=2459
2455 fnlib-0.4 ansic=2432,sh=23
2447 sliplogin-2.1.1 ansic=2256,sh=143,perl=48
2424 raidtools-0.90 ansic=2418,sh=6
2423 netkit-routed-0.16 ansic=2423
2407 nc ansic=1670,sh=737
2324 up2date-1.13 python=2324
2270 memprof-0.3.0 ansic=2270
2268 which-2.9 ansic=1398,sh=870
2200 printtool tcl=2200
2163 gnome-linuxconf-0.25 ansic=2163
2141 unarj-2.43 ansic=2141
2065 units-1.55 ansic=1963,perl=102
2048 netkit-ntalk-0.16 ansic=2048
1987 cracklib,2.7 ansic=1919,perl=46,sh=22
1984 cleanfeed-0.95.7b perl=1984
1977 wmconfig-0.9.8 ansic=1941,sh=36
1941 isicom ansic=1898,sh=43
1883 slocate-2.1 ansic=1802,sh=81
1857 netkit-rusers-0.16 ansic=1857
1856 pump-0.7.8 ansic=1856
1842 cdecl-2.5 ansic=1002,yacc=765,lex=75
1765 fbset-2.1 ansic=1401,yacc=130,lex=121,perl=113
1653 adjtimex-1.9 ansic=1653
1634 netcfg-2.25 python=1632,sh=2
1630 psmisc ansic=1624,sh=6
1621 urlview-0.7 ansic=1515,sh=106
1604 fortune-mod-9708 ansic=1604
1531 netkit-tftp-0.16 ansic=1531
1525 logrotate-3.3.2 ansic=1524,sh=1
1473 traceroute-1.4a5 ansic=1436,awk=37
1452 time-1.7 ansic=1395,sh=57
1435 ncompress-4.2.4 ansic=1435
1361 mt-st-0.5b ansic=1361
1290 cxhextris ansic=1290
1280 pam_krb5-1 ansic=1280
1272 bsd-finger-0.16 ansic=1272
1229 hdparm-3.6 ansic=1229
1226 procinfo-17 ansic=1145,perl=81
1194 passwd-0.64.1 ansic=1194
1182 auth_ldap-1.4.0 ansic=1182
1146 prtconf-1.3 ansic=1146
1143 anacron-2.1 ansic=1143
1129 xbill-2.0 cpp=1129
1099 popt-1.4 ansic=1039,sh=60
1088 nag perl=1088
1076 stylesheets-0.13rh perl=888,sh=188
1075 authconfig-3.0.3 ansic=1075
1049 kpppload-1.04 cpp=1044,sh=5
1020 MAKEDEV-2.5.2 sh=1020
1013 trojka ansic=1013
987 xmailbox-2.5 ansic=987
967 netkit-rwho-0.16 ansic=967
953 switchdesk-2.1 ansic=314,perl=287,cpp=233,sh=119
897 portmap_4 ansic=897
874 ldconfig-1999-02-21 ansic=874
844 jpeg-6b sh=844
834 ElectricFence-2.1 ansic=834
830 mouseconfig-4.4 ansic=830
816 rpmlint-0.8 python=813,sh=3
809 kdpms-0.2.8 cpp=809
797 termcap-2.0.8 ansic=797
787 xsysinfo-1.7 ansic=787
770 giftrans-1.12.2 ansic=770
742 setserial-2.15 ansic=742
728 tree-1.2 ansic=728
717 chkconfig-1.1.2 ansic=717
682 lpg perl=682
657 eject-2.0.2 ansic=657
616 diffstat-1.27 ansic=616
592 netscape-4.72 sh=592
585 usernet-1.0.9 ansic=585
549 genromfs-0.3 ansic=549
548 tksysv-1.1 tcl=526,sh=22
537 minlabel-1.2 ansic=537
506 netkit-bootparamd-0.16 ansic=506
497 locale_config-0.2 ansic=497
491 helptool-2.4 perl=288,tcl=203
480 elftoaout-2.2 ansic=480
463 tmpwatch-2.2 ansic=311,sh=152
445 rhs-printfilters-1.63 sh=443,ansic=2
441 audioctl ansic=441
404 control-panel-3.13 ansic=319,tcl=85
368 kbdconfig-1.9.2.4 ansic=368
368 vlock-1.3 ansic=368
367 timetool-2.7.3 tcl=367
347 kernelcfg-0.5 python=341,sh=6
346 timeconfig-3.0.3 ansic=318,sh=28
343 mingetty-0.9.4 ansic=343
343 chkfontpath-1.7 ansic=343
332 ethtool-1.0 ansic=332
314 mkbootdisk-1.2.5 sh=314
302 symlinks-1.2 ansic=302
301 xsri-1.0 ansic=301
294 netkit-rwall-0.16 ansic=294
290 biff+comsat-0.16 ansic=290
288 mkinitrd-2.4.1 sh=288
280 stat-1.5 ansic=280
265 sysreport-1.0 sh=265
261 bdflush-1.5 ansic=202,asm=59
255 ipvsadm-1.1 ansic=255
255 sag-0.6-html perl=255
245 man-pages-1.28 sh=244,sed=1
240 open-1.4 ansic=240
236 xtoolwait-1.2 ansic=236
222 utempter-0.5.2 ansic=222
222 mkkickstart-2.1 sh=222
221 hellas sh=179,perl=42
213 rhmask ansic=213
159 quickstrip-1.1 ansic=159
132 rdate-1.0 ansic=132
131 statserial-1.1 ansic=121,sh=10
107 fwhois-1.00 ansic=107
85 mktemp-1.5 ansic=85
82 modemtool-1.21 python=73,sh=9
67 setup-1.2 ansic=67
56 shaper ansic=56
52 sparc32-1.1 ansic=52
47 intimed-1.10 ansic=47
23 locale-ja-9 sh=23
16 AnotherLevel-1.0.1 sh=16
11 words-2 sh=11
7 trXFree86-2.1.2 tcl=7
0 install-guide-3.2.html (none)
0 caching-nameserver-6.2 (none)
0 XFree86-ISO8859-2-1.0 (none)
0 rootfiles (none)
0 ghostscript-fonts-5.50 (none)
0 kudzu-0.36 (none)
0 wvdial-1.41 (none)
0 mailcap-2.0.6 (none)
0 desktop-backgrounds-1.1 (none)
0 redhat-logos (none)
0 solemul-1.1 (none)
0 dev-2.7.18 (none)
0 urw-fonts-2.0 (none)
0 users-guide-1.0.72 (none)
0 sgml-common-0.1 (none)
0 setup-2.1.8 (none)
0 jadetex (none)
0 gnome-audio-1.0.0 (none)
0 specspo-6.2 (none)
0 gimp-data-extras-1.0.0 (none)
0 docbook-3.1 (none)
0 indexhtml-6.2 (none)
ansic: 14218806 (80.55%)
cpp: 1326212 (7.51%)
lisp: 565861 (3.21%)
sh: 469950 (2.66%)
perl: 245860 (1.39%)
asm: 204634 (1.16%)
tcl: 152510 (0.86%)
python: 140725 (0.80%)
yacc: 97506 (0.55%)
java: 79656 (0.45%)
exp: 79605 (0.45%)
lex: 15334 (0.09%)
awk: 14705 (0.08%)
objc: 13619 (0.08%)
csh: 10803 (0.06%)
ada: 8217 (0.05%)
pascal: 4045 (0.02%)
sed: 2806 (0.02%)
fortran: 1707 (0.01%)
Total Physical Source Lines of Code (SLOC) = 17652561
Total Estimated Person-Years of Development = 4548.36
Average Programmer Annual Salary = 56286
Overhead Multiplier = 2.4
Total Estimated Cost to Develop = $ 614421924.71
B.2 Counts of Files For Each Category
There were 181,679 ordinary files in the build directory. The following are counts of the number of files (not the SLOC) for each language:
ansic: 52088 (71.92%) cpp: 8092 (11.17%) sh: 3381 (4.67%) asm: 1931 (2.67%) perl: 1387 (1.92%) lisp: 1168 (1.61%) java: 1047 (1.45%) python: 997 (1.38%) tcl: 798 (1.10%) exp: 472 (0.65%) awk: 285 (0.39%) objc: 260 (0.36%) sed: 112 (0.15%) yacc: 110 (0.15%) csh: 94 (0.13%) ada: 92 (0.13%) lex: 57 (0.08%) fortran: 50 (0.07%) pascal: 7 (0.01%) Total Number of Source Code Files = 72428
In addition, when counting the number of files (not SLOC), some files were identified as source code files but nevertheless were not counted for other reasons (and thus not included in the file counts above). Of these source code files, 5,820 files were identified as duplicating the contents of another file, 817 files were identified as files that had been automatically generated, and 65 files were identified as zero-length files.
B.3 Additional Measures of the Linux Kernel
I also made additional measures of the Linux kernel. This kernel is Linux kernel version 2.2.14 as patched by Red Hat. The Linux kernel's design is reflected in its directory structure. Only 8 lines of source code are in its main directory; the rest are in descendent directories. Counting the physical SLOC in each subdirectory (or its descendents) yielded the following:BUILD/linux/Documentation/ 765 BUILD/linux/arch/ 236651 BUILD/linux/configs/ 0 BUILD/linux/drivers/ 876436 BUILD/linux/fs/ 88667 BUILD/linux/ibcs/ 16619 BUILD/linux/include/ 136982 BUILD/linux/init/ 1302 BUILD/linux/ipc/ 1757 BUILD/linux/kernel/ 7436 BUILD/linux/ksymoops-0.7c/ 3271 BUILD/linux/lib/ 1300 BUILD/linux/mm/ 6771 BUILD/linux/net/ 105549 BUILD/linux/pcmcia-cs-3.1.8/ 34851 BUILD/linux/scripts/ 8357
I separately ran the CodeCount tools on the entire linux operating system kernel. Using the CodeCount definition of C logical lines of code, CodeCount determined that this version of the linux kernel included 673,627 logical SLOC in C. This is obviously much smaller than the 1,462,165 of physical SLOC in C, or the 1,526,722 SLOC when all languages are combined for Linux.
However, this included non-i86 code. To make a more reasonable comparison with the Halloween documents, I needed to ignore non-i386 code.
First, I looked at the linux/arch directory, which contained architecture-specific code. This directory had the following subdirectories (architectures): alpha, arm, i386, m68k, mips, ppc, s390, sparc, sparc64. I then computed the total for all of ``arch'', which was 236651 SLOC, and subtracted out linux/arch/i386 code, which totalled to 26178 SLOC; this gave me a total of non-i386 code in linux/arc as 210473 physical SLOC. I then looked through the ``drivers'' directory to see if there were sets of drivers which were non-i386. I identified the following directories, with the SLOC totals as shown:
linux/drivers/sbus/ 22354 linux/drivers/macintosh/ 6000 linux/drivers/sgi/ 4402 linux/drivers/fc4/ 3167 linux/drivers/nubus/ 421 linux/drivers/acorn/ 11850 linux/drivers/s390/ 8653 Driver Total: 56847Thus, I had a grand total on non-i86 code (including drivers and architecture-specific code) as 267320 physical SLOC. This is, of course, another approximation, since there's certainly other architecture-specific lines, but I believe that is most of it. Running the CodeCount tool on just the C code, once these architectural and driver directories are removed, reveals a logical SLOC of 570,039 of C code.
B.4 Minimum System SLOC
Most of this paper worries about counting an ``entire'' system. However, what's the SLOC size of a ``minimal'' system? Here's an attempt to answer that question.Red Hat Linux 6.2, CD-ROM #1, file RedHat/base/comps, defines the ``base'' (minimum) Red Hat Linux 6.2 installation as a set of packages. The following are the build directories corresponding to this base (minimum) installation, along with the SLOC counts (as shown above). Note that this creates a text-only system:
Component SLOC anacron-2.1 1143 apmd 3012 ash-linux-0.2 9666 at-3.1.7 3084 authconfig-3.0.3 1075 bash-1.14.7 47067 bc-1.05 17682 bdflush-1.5 261 binutils-2.9.5.0.22 467120 bzip2-0.9.5d 4996 chkconfig-1.1.2 717 console-tools-0.3.3 15522 cpio-2.4.2 7617 cracklib,2.7 1987 dev-2.7.18 0 diffutils-2.7 10914 dump-0.4b15 10187 e2fsprogs-1.18 28169 ed-0.2 7427 egcs-1.1.2 720112 eject-2.0.2 657 file-3.28 2647 fileutils-4.0p 34768 findutils-4.1 11404 gawk-3.0.4 26363 gd1.3 20078 gdbm-1.8.0 3315 getty_ps-2.0.7j 2631 glibc-2.1.3 415026 gmp-2.0.2 24583 gnupg-1.0.1 54935 gpm-1.18.1 9725 grep-2.4 10013 groff-1.15 70260 gzip-1.2.4a 6306 hdparm-3.6 1229 initscripts-5.00 3929 isapnptools-1.21 5960 kbdconfig-1.9.2.4 368 kernelcfg-0.5 347 kudzu-0.36 0 ldconfig-1999-02-21 874 ld.so-1.9.5 9731 less-346 14039 lilo 7255 linuxconf-1.17r2 104032 logrotate-3.3.2 1525 mailcap-2.0.6 0 mailx-8.1.1 6968 MAKEDEV-2.5.2 1020 man-1.5h1 9801 mingetty-0.9.4 343 mkbootdisk-1.2.5 314 mkinitrd-2.4.1 288 mktemp-1.5 85 modutils-2.3.9 11775 mouseconfig-4.4 830 mt-st-0.5b 1361 ncompress-4.2.4 1435 ncurses-5.0 61324 net-tools-1.54 11633 newt-0.50.8 7041 pam-0.72 20433 passwd-0.64.1 1194 pciutils-2.1.5 3855 popt-1.4 1099 procmail-3.14 9927 procps-2.0.6 9961 psmisc 1630 pump-0.7.8 1856 pwdb-0.61 9551 quota-2.00-pre3 3804 raidtools-0.90 2424 readline-2.2.1 14941 redhat-logos 0 rootfiles 0 rpm-3.0.4 39861 sash-3.4 6172 sed-3.02 7740 sendmail-8.9.3 42880 setserial-2.15 742 setup-1.2 67 setup-2.1.8 0 shadow-19990827 25236 sh-utils-2.0 17939 slang 28118 slocate-2.1 1883 stat-1.5 280 sysklogd-1.3-31 4038 sysvinit-2.78 6033 tar-1.13.17 14255 termcap-2.0.8 797 texinfo-4.0 28186 textutils-2.0a 36338 time-1.7 1452 timeconfig-3.0.3 346 tmpwatch-2.2 463 utempter-0.5.2 222 util-linux-2.10f 39160 vim-5.6 113241 vixie-cron-3.0.1 2879 which-2.9 2268 zlib-1.1.3 4087
Thus, the contents of the build directories corresponding to the ``base'' (minimum) installation totals to 2,819,334 SLOC.
A few notes are in order about this build directory total:
- Some of the packages listed by a traditional package list aren't shown here because they don't contain any code. Package "basesystem" is a pseudo-package for dependency purposes. Package redhat-release is just a package for keeping track of the base system's version number. Package "filesystem" contains a directory layout.
- ntsysv's source is in chkconfig-1.1.2; kernel-utils and kernel-pcmcia-cs are part of "linux". Package shadow-utils is in build directory shadow-19990827. Build directory util-linux includes losetup and mount. "dump" is included to include rmt.
- Sometimes the build directories contain more code than is necessary to create just the parts for the ``base'' system; this is a side-effect of how things are packaged. ``info'' is included in the base, so we count all of texinfo. The build directory termcap is counted, because libtermcap is in the base. Possibly most important, gcc (egcs) is there because libstdc++ is in the base.
- Sometimes a large component is included in the base, even though most of the time little of its functionality is used. In particular, the mail transfer agent ``sendmail'' is in the base, even though for many users most of sendmail's functionality isn't used. However, for this paper's purposes this isn't a problem. After all, even if sendmail's functionality is often underused, clearly that functionality took time to develop and that functionality is available to those who want it.
- My tools intentionally eliminated duplicates; it may be that a few files aren't counted here because they're considered duplicates of another build directory not included here. I do not expect this factor to materially change the total.
- Red Hat Linux is not optimized to be a ``small as possible'' distribution; their emphasis is on functionality, not small size. A working Linux distribution could include much less code, depending on its intended application. For example, ``linuxconf'' simplifies system configuration, but the system can be configured by editing its system configuration files directly, which would reduce the base system's size. This also includes vim, a full-featured text editor - a simpler editor with fewer functions would be smaller as well.
Many people prefer some sort of graphical interface; here is a minimal configuration of a graphical system, adding the X server, a window manager, and a few tools:
| Component | SLOC |
| XFree86-3.3.6 | 1291745 |
| Xconfigurator-4.3.5 | 9741 |
| fvwm-2.2.4 | 69265 |
| X11R6-contrib-3.3.2 | 18885 |
Adding these numbers together, we now have a total of 4,208,970 SLOC for a ``minimal graphical system.'' Many people would want to add more components. For example, this doesn't include a graphical toolkit (necessary for running most graphical applications). We could add gtk+-1.2.6 (a toolkit needed for running GTK+ based applications), adding 138,118 SLOC. This would now total 4,347,088 for a ``basic graphical system,'' one able to run basic GTK+ applications.
Let's add a web server to the mix. Adding apache_1.3.12 adds only 77,873 SLOC. We now have 4,424,961 physical SLOC for a basic graphical system plus a web server.
We could then add a graphical desktop environment, but there are so many different options and possibilities that trying to identify a ``minimal'' system is hard to do without knowing the specific uses intended for the system. Red Hat defines a standard ``GNOME'' and ``KDE'' desktop, but these are intended to be highly functional (not ``minimal''). Thus, we'll stop here, with a total of 2.8 million physical SLOC for a minimal text-based system, and total of 4.4 million physical SLOC for a basic graphical system plus a web server.
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This paper is (C) Copyright 2000 David A. Wheeler. All rights reserved. You may download and print it for your own personal use, and of course you may link to it. When referring to the paper, please refer to it as ``Estimating GNU/Linux's Size'' by David A. Wheeler, located at http://www.dwheeler.com/sloc. Please give credit if you refer to any of its techniques or results.