Что такое dot linux

The shell shall execute commands from the file in the current environment.

If file does not contain a slash, the shell shall use the search path specified by PATH to find the directory containing file . Unlike normal command search, however, the file searched for by the dot utility need not be executable. If no readable file is found, a non-interactive shell shall abort; an interactive shell shall write a diagnostic message to standard error, but this condition shall not be considered a syntax error.

OPTIONS

OPERANDS

See the DESCRIPTION.

STDIN

INPUT FILES

See the DESCRIPTION.

ENVIRONMENT VARIABLES

See the DESCRIPTION.

ASYNCHRONOUS EVENTS

STDOUT

STDERR

The standard error shall be used only for diagnostic messages.

OUTPUT FILES

EXTENDED DESCRIPTION

EXIT STATUS

Returns the value of the last command executed, or a zero exit status if no command is executed.

CONSEQUENCES OF ERRORS

The following sections are informative.

APPLICATION USAGE

EXAMPLES

RATIONALE

Some older implementations searched the current directory for the file , even if the value of PATH disallowed it. This behavior was omitted from this volume of IEEE Std 1003.1-2001 due to concerns about introducing the susceptibility to trojan horses that the user might be trying to avoid by leaving dot out of PATH .

The KornShell version of dot takes optional arguments that are set to the positional parameters. This is a valid extension that allows a dot script to behave identically to a function.

Источник

Переменные окружения и конфигурационные dot-файлы

Для одноразовой параметризации выполнения команд служат их индивидуальные ключи, указываемые каждый раз при запуске команды, но иногда требуется установить некий параметр, который бы действовал в течение всего сеанса работы пользователя с системой, или общий параметр, который действовал бы для всех команд, запускаемых в сеансе.

Таким механизмом является окружение environ(7) и переменные окружения, значения которых можно увидеть при помощи команды env(1). Переменные окружения обычно документируются на странице руководства к тем программам, на которые воздействуют, как правило, в разделе ENVIRONMENT.

Например, переменная окружения PATH содержит перечисление разделенных символом : имен каталогов, где любой командный интерпретатор ищет одноименные запускаемым командам программы.

Переменная окружения PATH

$ date

Вт. марта 14 01:23:47 MSK 2018

$ help -d unset

unset — Unset values and attributes of shell variables and functions.

$ unset PATH

$ date

bash: date: Нет такого файла или каталога

Переменная окружения lang содержит идентификатор языка, на котором программы стараются общаться с пользователем, например man(1) ищет перевод страницы руководства.

Переменная окружения LANG

$ LANG=ja_JP.UTF-8

$ date

2018* 8 12 17:25:09 MSK

$ LANG=ka_GE.UTF-8

6 7 8 9 10 11 12

13 14 15 16 17 18 19

20 21 22 23 24 25 26

$ unset LANG

$ whatis man

man (7) — macros to format man pages

man (1) — an interface to the on-line reference manuals

$ export LANG=ru_RU.UTF-8

$ whatis man

man (1) — доступ к справочным страницам

man (7) — macros to format man pages

Переменная окружения pager указывает имя программы «листателя», использующегося другими программами, вывод которых не умещается на один экран. Так, например, поступает man(1) при отображении отформатированной страницы руководства, mail(1) при просмотре длинного письма, mysql(1) или psql(1) при выводе большого количества результирующих строк ответа за запрос к базе данных. Наиболее распространенным листателем является less(1), используемый как замена менее удобного «классического» more(1).

Переменные окружения EDITOR и VISUAL указывают имя текстового редактора, который будет вызван другими программами при необходимости редактировать текст.

Например, crontab(1) использует указанный таким образом редактор для изменения списка периодических заданий, mail(1) для редактирования отправляемого сообщения, mysql(1) или psql(1) для редактирования длинных запросов к базе данных, а lftp(1) для редактирования списка «закладок». Очень часто в качестве редактора используется «классический» и достаточно непривычный vi(1), который можно таким образом заменить более удобным nano(1).

Переменная browser указывает имя просмотрщика HTML, который будет использован другими программами при необходимости показать HTML-страницу, например, отформатированную таким образом страницу руководства man(1).

Переменная окружения BROWSER

$ man -Н Is

sh: 1: exec: www-browser: not found

man: couldn’t execute any browser from exec www-browser

$ export BROWSER=chromium-browser

$ man -H Is

В текущем сеансе браузера создано новое окно.

Некоторые программы имеют специальную переменную окружения, которая содержит ключи, применяемые каждый раз при вызове программы, например MANOPT для man(1). Такие переменные для программ XXX чаще всего имеют имя или XXX_OPTIONS или даже XXX, например ZIPOPT для zip(1), TAR_OPTIONS для tar(1), GZIP для gzip(1) и LESS/MORE для less(1) и more(1) соответственно.

Установив, например, MANOPT=-H (BROWSER=chromium-browser, или BROWSER=firefox, или BROWSER=links, или BROWSER=lynx), можно просматривать страницы руководства в (одном из указанных графическом и/или текстовом) Web-браузере, а установив GZIP=-9, можно заставить упаковщик всегда использовать девятую (самую сильную, но самую медленную) степень сжатия.

Переменная окружения PS1 изменяет приглашение командного интерпретатора и может содержать подстановки (документированные в bash(1)), например,

\u — имя зарегистрированного в системе пользователя,
\h — короткое собственное имя компьютера,
\w— имя текущего каталога,
\$— символ приглашения $ для обычного пользователя и # для Суперпользователя root,
\t — время в 24-часовом формате,
\e— управляющий символ ESC и пр.

Используя подстановки PS1 и управляющие ESC-последовательности console_codes(7) или воспользовавшись базой данных управляющих ESC-последовательностей terminfo(5) и командой tput(1), можно модифицировать приглашение по своему предпочтению.

Переменная окружения РS1

$ man 5 terminfo

enter_reverse_mode rev mr turn on reverse
video mode

. . . . . . . . .
enter_dim_node dim mh turn on half-bright
mode

. . . . . . . . .
exit_attribute_mode sgr0 me turn off all
attributes

$ tput rev | od -a

$ tput dim | od -a

$ tput sgr0 | od -a

0000000 esc [ В esc [ m

Или даже можно воспользоваться поддержкой символов unicode(7) в UTF-8(7) представлении на терминале. В этом примере эмулятор терминала в графическом интерфейсе по умолчанию имеет нужные шрифты, а на консоли необходимо загрузить подходящий Unicode-шрифт, например, командой setfont Uni2-Ternimus16.

Переменная окружения РS1 (вариант 2)

$ stty

speed 38400 baud; line = 0;

eol = M-^?; eol2 = M-^?; swtch = M-^?;

$ PS1=’ \u\342\230\273 \h:\w\$ ‘

Переменная окружения term устанавливает Имя терминала, по которому программы, использующие управляющие ESC-последовательности (например, файловый менеджер mc(1)), берут их значения из базы данных terminfo(5).

Для эмуляторов терминала в графическом интерфейсе ее значение обычно TERM=xterm или TERM=xterm-color, для консоли Linux TERM=linux, а для настоящего аппаратного терминала W: [VT100] TERM=vt1oo. При неправильном значении переменной, например, могут «перестать работать» функциональные клавиши, просто потому что программа будет ожидать поступление определенной ESC-последовательности, соответствующей функциональной клавише, а в реальности будет поступать другая.

Переменная окружения TERM

$ env

$ TERM=linux

$ infocmp

$ od -a
F2↵
^D
0000000 esc О Q nl

Стоит отметить, что переменные окружения сохраняют свои установленные значения в оперативной памяти командного интерпретатора и теряют их при завершении сеанса. Для установки постоянных значений параметров программ логично поместить их в какое-либо долгосрочное хранилище, например в файлы на диске.

Специальные файлы и каталоги, сохраняющие конфигурационные параметры, по соглашению имеют имена, начинающиеся с точки (dot— точка), располагаются в домашнем каталоге пользователя и носят название dot-файлов.

Конфигурационные dot-файлы

. . .
.bash_history
.bash_logout
.bashrc

$ file .profile .bashrc .lftp .ssh

.profile: ASCII English text

.bashrc: ASCII English text

.lftp: directory
.ssh: directory

Некоторые программы, например lftp(1), ssh(1) или ssh(1), имеют собственные конфигурационные файлы и/или каталоги, тогда как простейшие less(1), tar(1) и zip(1) предполагают, что «постоянные» параметры по-прежнему задаются при помощи переменных окружения less, tar_options и zipopt.

В таких случаях «постоянные» значения переменных сохраняются в каком-либо конфигурационном файле командного интерпретатора bash, например, считываемом в начале сеанса— .profile или при каждом запуске— .bashrc.

Конфигурационные dot-файлы интерпретатора bash

Конфигурационные dot-файлы представляют собой текст на некотором языке, понятном конфигурируемой программе, например, язык командного интерпретатора bash(1) используется в .profile и .bashrc.

В большинстве случаев имена dot-файлов и их язык документируются в страницах руководства к «их» программам, обычно в разделе FILES. Нередко конфигурационному файлу посвящается отдельная страница в пятой секции, например, nanorc(5) для dot-файла .nanorc текстового редактора nano(1) или netrc(5) для файла .netrc FTP-клиентов ftp(1) и lftp(1), или ssh_config(5) для .ssh/config SSH-клиента ssh(1).

В отдельных случаях, когда конфигурируется не конкретная программа, а общая для многих программ библиотека, например readline(3), название переменных окружения, имя и язык конфигурационного файла можно получить (INPUTRC и .inputrc для readline(3), соответственно) из страницы руководства самой библиотеки.

Источник

dot(1) — Linux man page

Synopsis

Description

neato draws undirected graphs using »spring» models (see Kamada and Kawai, Information Processing Letters 31:1, April 1989). Input files must be formatted in the dot attributed graph language. By default, the output of neato is the input graph with layout coordinates appended.

twopi draws graphs using a radial layout (see G. Wills, Symposium on Graph Drawing GD’97, September, 1997). Basically, one node is chosen as the center and put at the origin. The remaining nodes are placed on a sequence of concentric circles centered about the origin, each a fixed radial distance from the previous circle. All nodes distance 1 from the center are placed on the first circle; all nodes distance 1 from a node on the first circle are placed on the second circle; and so forth.

circo draws graphs using a circular layout (see Six and Tollis, GD ’99 and ALENEX ’99, and Kaufmann and Wiese, GD ’02.) The tool identifies biconnected components and draws the nodes of the component on a circle. The block-cutpoint tree is then laid out using a recursive radial algorithm. Edge crossings within a circle are minimized by placing as many edges on the circle’s perimeter as possible. In particular, if the component is outerplanar, the component will have a planar layout.

If a node belongs to multiple non-trivial biconnected components, the layout puts the node in one of them. By default, this is the first non-trivial component found in the search from the root component.

fdp draws undirected graphs using a »spring» model. It relies on a force-directed approach in the spirit of Fruchterman and Reingold (cf. Software-Practice & Experience 21(11), 1991, pp. 1129-1164).

sfdp also draws undirected graphs using the »spring» model described above, but it uses a multi-scale approach to produce layouts of large graphs in a reasonably short time.

Output Formats

Traditionally, dot supports the following: -Tps (PostScript), -Tsvg -Tsvgz (Structured Vector Graphics), -Tfig (XFIG graphics), -Tmif (FrameMaker graphics), -Thpgl (HP pen plotters), and -Tpcl (Laserjet printers), -Tpng -Tgif (bitmap graphics), -Tdia (GTK+ based diagrams), -Timap (imagemap files for httpd servers for each node or edge that has a non-null «href» attribute.), -Tcmapx (client-side imagemap for use in html and xhtml). Additional less common or more special-purpose output formats can be found at http://www.graphviz.org/cvs/doc/info/output.html.)

Alternative plugins providing support for a given output format can be found from the error message resulting from appending a ‘:’ to the format. e.g. -Tpng: The first plugin listed is always the default.

The -P switch can be used to produce a graph of all output variants supported by plugins in the local installation of graphviz.

Graph File Language

[strict] (graph|digraph) name < statement-list >
Is the top level graph. If the graph is strict then multiple edges are not allowed between the same pairs of nodes. If it is a directed graph, indicated by digraph, then the edgeop must be «->». If it is an undirected graph then the edgeop must be «—«. Statements may be:

name=val;
node [name=val];
edge [name=val];
Set default graph, node, or edge attribute name to val. Any subgraph, node, or edge appearing after this inherits the new default attributes.

n0 [name0=val0,name1=val1. ]; Creates node n0 (if it does not already exist) and sets its attributes according to the optional list.

n0 edgeop n1 edgeop . edgeop nn [name0=val0,name1=val1. ];
Creates edges between nodes n0, n1, . nn and sets their attributes according to the optional list. Creates nodes as necessary.

[subgraph name] < statement-list >
Creates a subgraph. Subgraphs may be used in place of n0, . nn in the above statements to create edges. [subgraph name] is optional; if missing, the subgraph is assigned an internal name.

Comments may be /*C-like*/ or //C++-like.

Attribute names and values are ordinary (C-style) strings. The following sections describe attributes that control graph layout.

Graph Attributes

size=»x,y» sets bounding box of drawing in inches.

page=»x,y» sets the PostScript pagination unit.

ratio=f sets the aspect ratio to f which may be a floating point number, or one of the keywords fill, compress, or auto.

layout=engine indicates the preferred layout engine («dot», «neato», fdp» etc) overriding the default from the basename of the command or the -K commandline option.

margin=f sets the page margin (included in the page size).

nodesep=f sets the minimum separation between nodes.

ranksep=f sets the minimum separation between ranks.

ordering=out constrains order of out-edges in a subgraph according to their file sequence.

rankdir=LR|RL|BT requests a left-to-right, right-to-left, or bottom-to-top, drawing.

pagedir=[TBLR][TBLR] sets the major and minor order of pagination.

rank=same (or min or max) in a subgraph constrains the rank assignment of its nodes. If a subgraph’s name has the prefix cluster, its nodes are drawn in a distinct rectangle of the layout. Clusters may be nested.

rotate=90 sets landscape mode. (orientation=land is backward compatible but obsolete.)

center=n a non-zero value centers the drawing on the page.

nslimit=f or mclimit=f adjusts the bound on the number of network simplex or mincross iterations by the given ratio. For example, mclimit=2.0 runs twice as long.

layers=»id:id:id:id» is a sequence of layer identifiers for overlay diagrams. The PostScript array variable layercolorseq sets the assignment of colors to layers. The least index is 1 and each element must be a 3-element array to be interpreted as a color coordinate.

color=colorvalue sets foreground color (bgcolor for background).

href=«url» the default url for image map files; in PostScript files, the base URL for all relative URLs, as recognized by Acrobat Distiller 3.0 and up.

URL=«url» («URL» is a synonym for «href».)

stylesheet=«file.css» includes a reference to a stylesheet in -Tsvg and -Tsvgz outputs. Ignored by other formats.

splines. If set to true, edges are drawn as splines. If set to polyline, edges are drawn as polylines. If set to ortho, edges are drawn as orthogonal polylines. In all of these cases, the nodes may not overlap. If splines=false or splines=line, edges are drawn as line segments. The default is true for dot, and false for all other layouts.

(neato-specific attributes)
start=val. Requests random initial placement and seeds the random number generator. If val is not an integer, the process ID or current time is used as the seed.

epsilon=n. Sets the cutoff for the solver. The default is 0.1.

(twopi-specific attributes)
root=ctr. This specifies the node to be used as the center of the layout. If not specified, twopi will randomly pick one of the nodes that are furthest from a leaf node, where a leaf node is a node of degree 1. If no leaf nodes exists, an arbitrary node is picked as center.

ranksep=val. Specifies the radial distance in inches between the sequence of rings. The default is 0.75.

overlap=mode. This specifies what twopi should do if any nodes overlap. If mode is «false», the program uses Voronoi diagrams to adjust the nodes to eliminate overlaps. If mode is «scale», the layout is uniformly scaled up, preserving node sizes, until nodes no longer overlap. The latter technique removes overlaps while preserving symmetry and structure, while the former removes overlaps more compactly but destroys symmetries. If mode is «true» (the default), no repositioning is done.

(circo-specific attributes)
root=nodename. Specifies the name of a node occurring in the root block. If the graph is disconnected, the root node attribute can be used to specify additional root blocks.

mindist=value. Sets the minimum separation between all nodes. If not specified then circo uses a default value of 1.0.

(fdp-specific attributes)
K=val. Sets the default ideal node separation in the layout.

maxiter=val. Sets the maximum number of iterations used to layout the graph.

start=val. Adjusts the random initial placement of nodes with no specified position. If val is is an integer, it is used as the seed for the random number generator. If val is not an integer, a random system-generated integer, such as the process ID or current time, is used as the seed.

Node Attributes

height=d or width=d sets minimum height or width. Adding fixedsize=true forces these to be the actual size (text labels are ignored).

shape=record polygon epsf builtin_polygon
builtin_polygon is one of: plaintext ellipse oval circle egg triangle box diamond trapezium parallelogram house hexagon octagon note tab box3d component. (Polygons are defined or modified by the following node attributes: regular, peripheries, sides, orientation, distortion and skew.) epsf uses the node’s shapefile attribute as the path name of an external EPSF file to be automatically loaded for the node shape.

label=text where text may include escaped newlines \n, \l, or \r for center, left, and right justified lines. The string ‘\N’ value will be replaced by the node name. The string ‘\G’ value will be replaced by the graph name. Record labels may contain recursive box lists delimited by < | >. Port identifiers in labels are set off by angle brackets . In the graph file, use colon (such as, node0:port28).

fontsize=n sets the label type size to n points.

fontname=name sets the label font family name.

color=colorvalue sets the outline color, and the default fill color if style=filled and fillcolor is not specified.

fillcolor=colorvalue sets the fill color when style=filled. If not specified, the fillcolor when style=filled defaults to be the same as the outline color.

fontcolor=colorvalue sets the label text color.

A colorvalue may be «h,s,v« (hue, saturation, brightness) floating point numbers between 0 and 1, or an X11 color name such as white black red green blue yellow magenta cyan or burlywood, or a «#rrggbb» (red, green, blue, 2 hex characters each) value.

style=filled solid dashed dotted bold invis or any Postscript code.

layer=id or id:id or «all» sets the node’s active layers. The empty string means no layers (invisible).

The following attributes apply only to polygon shape nodes:

regular=n if n is non-zero then the polygon is made regular, i.e. symmetric about the x and y axis, otherwise the polygon takes on the aspect ratio of the label. builtin_polygons that are not already regular are made regular by this attribute. builtin_polygons that are already regular are not affected (i.e. they cannot be made asymmetric).

peripheries=n sets the number of periphery lines drawn around the polygon. This value supersedes the number of periphery lines of builtin_polygons.

sides=n sets the number of sides to the polygon. n head_node_name If the substring ‘\G’ is found in a label it will be replaced by the graph name. or by: tail_node_name—head_node_name for undirected graphs.

fontsize=n sets the label type size to n points.

fontname=name sets the label font family name.

fontcolor=colorvalue sets the label text color.

style=solid dashed dotted bold invis

color=colorvalue sets the line color for edges.

color=colorvaluelist a ‘:’ separated list of colorvalue creates parallel edges, one edge for each color.

dir=forward back both none controls arrow direction.

tailclip,headclip=false disables endpoint shape clipping.

href=«url» sets the url for the node in imagemap, PostScript and SVG files. The substrings ‘\T’, ‘\H’, ‘\E’ and ‘\G’ are substituted in the same manner as for the edge label attribute. Additionally the substring ‘\L’ is substituted with the edge label string.

URL=«url» («URL» is a synonym for «href».)

target=«target» is a target string for client-side imagemaps and SVG, effective when edges have a URL. If the target string is empty, the default, then no target attribute is included in the output. The substrings ‘\T’, ‘\H’, ‘\E’ and ‘\G’ are substituted in the same manner as for the edge label attribute. Additionally the substring ‘\L’ is substituted with the edge label string.

tooltip=«tooltip» is a tooltip string for client-side imagemaps effective when edges have a URL. The tooltip string defaults to be the same as the edge label string. The substrings ‘\T’, ‘\H’, ‘\E’ and ‘\G’ are substituted in the same manner as for the edge label attribute. Additionally the substring ‘\L’ is substituted with the edge label string.

arrowhead,arrowtail=none, normal, inv, dot, odot, invdot, invodot, tee, empty, invempty, open, halfopen, diamond, odiamond, box, obox, crow.

arrowsize (norm_length=10,norm_width=5, inv_length=6,inv_width=7,dot_radius=2)

headlabel,taillabel=string for port labels. labelfontcolor,labelfontname,labelfontsize for head and tail labels. The substrings ‘\T’, ‘\H’, ‘\E’ and ‘\G’ are substituted in the same manner as for the edge label attribute. Additionally the substring ‘\L’ is substituted with the edge label string.

headhref=«url» sets the url for the head port in imagemap, PostScript and SVG files. The substrings ‘\T’, ‘\H’, ‘\E’ and ‘\G’ are substituted in the same manner as for the edge label attribute. Additionally the substring ‘\L’ is substituted with the edge label string.

headURL=«url» («headURL» is a synonym for «headhref».)

headtarget=«headtarget» is a target string for client-side imagemaps and SVG, effective when edge heads have a URL. The headtarget string is used to determine which window of the browser is used for the URL. If the headtarget string is empty, the default, then headtarget defaults to the same value as target for the edge. The substrings ‘\T’, ‘\H’, ‘\E’ and ‘\G’ are substituted in the same manner as for the edge label attribute. Additionally the substring ‘\L’ is substituted with the edge label string.

headtooltip=«tooltip» is a tooltip string for client-side imagemaps effective when head ports have a URL. The tooltip string defaults to be the same as the headlabel string. The substrings ‘\T’, ‘\H’, and ‘\E’ are substituted in the same manner as for the edge label attribute. Additionally the substring ‘\L’ is substituted with the edge label string.

tailhref=«url» sets the url for the tail port in imagemap, PostScript and SVG files. The substrings ‘\T’, ‘\H’, ‘\E’ and ‘\G’ are substituted in the same manner as for the edge label attribute. Additionally the substring ‘\L’ is substituted with the edge label string.

tailURL=«url» («tailURL» is a synonym for «tailhref».)

tailtarget=«tailtarget» is a target string for client-side imagemaps and SVG, effective when edge tails have a URL. The tailtarget string is used to determine which window of the browser is used for the URL. If the tailtarget string is empty, the default, then tailtarget defaults to the same value as target for the edge. The substrings ‘\T’, ‘\H’, ‘\E’ and ‘\G’ are substituted in the same manner as for the edge label attribute. Additionally the substring ‘\L’ is substituted with the edge label string.

tailtooltip=«tooltip» is a tooltip string for client-side imagemaps effective when tail ports have a URL. The tooltip string defaults to be the same as the taillabel string. The substrings ‘\T’, ‘\H’, ‘\E’ and ‘\G’ are substituted in the same manner as for the edge label attribute. Additionally the substring ‘\L’ is substituted with the edge label string.

labeldistance and port_label_distance set distance; also labelangle (in degrees CCW)

decorate draws line from edge to label.

samehead,sametail aim edges having the same value to the same port, using the average landing point.

constraint=false causes an edge to be ignored for rank assignment.

layer=id or id:id or «all» sets the edge’s active layers. The empty string means no layers (invisible).

(neato-specific attributes)
w=f sets the weight (spring constant) of an edge to the given floating point value. The default is 1.0; greater values make the edge tend more toward its optimal length.

len=f sets the optimal length of an edge. The default is 1.0.

(fdp-specific attributes)
weight=f sets the weight of an edge to the given floating point value. The default is 1.0; greater values make the edge tend more toward its optimal length.

Command Line Options

-lfile loads custom PostScript library files. Usually these define custom shapes or styles. If -l is given by itself, the standard library is omitted.

-Tlang sets the output language as described above.

-n[1|2] (no-op) If set, neato assumes nodes have already been positioned and all nodes have a pos attribute giving the positions. It then performs an optional adjustment to remove node-node overlap, depending on the value of the overlap attribute, computes the edge layouts, depending on the value of the splines attribute, and emits the graph in the appropriate format. If num is supplied, the following actions occur: Equivalent to -n. Use node positions as specified, with no adjustment to remove node-node overlaps, and use any edge layouts already specified by the pos attribute. neato computes an edge layout for any edge that does not have a pos attribute. As usual, edge layout is guided by the splines attribute.

-Klayout override the default layout engine implied by the command name.

-O automatically generate output filenames based on the input filename and the -T format.

-P generate a graph of the currently available plugins.

-v (verbose) prints various information useful for debugging.

-V (version) prints version information and exits.

-? prints the usage and exits.

Examples

Caveats

Flat edge labels are slightly broken. Intercluster edge labels are totally broken.

Because unconstrained optimization is employed, node boxes can possibly overlap or touch unrelated edges. All existing spring embedders seem to have this limitation.

Apparently reasonable attempts to pin nodes or adjust edge lengths and weights can cause instability.

Authors

The bitmap driver (PNG, GIF etc) is by Thomas Boutell,

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