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<head>
<title>mk(1) - Plan 9 from User Space</title>
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</head>
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<table border=0 cellpadding=0 cellspacing=0 width=100%>
<tr height=10><td>
<tr><td width=20><td>
<tr><td width=20><td><b>MK(1)</b><td align=right><b>MK(1)</b>
<tr><td width=20><td colspan=2>
<br>
<p><font size=+1><b>NAME </b></font><br>
<table border=0 cellpadding=0 cellspacing=0><tr height=2><td><tr><td width=20><td>
mk – maintain (make) related files<br>
</table>
<p><font size=+1><b>SYNOPSIS </b></font><br>
<table border=0 cellpadding=0 cellspacing=0><tr height=2><td><tr><td width=20><td>
<tt><font size=+1>mk</font></tt> [ <tt><font size=+1>−f</font></tt> <i>mkfile</i> ] ... [ <i>option ...</i> ] [ <i>target ...</i> ]<br>
</table>
<p><font size=+1><b>DESCRIPTION </b></font><br>
<table border=0 cellpadding=0 cellspacing=0><tr height=2><td><tr><td width=20><td>
<i>Mk</i> uses the dependency rules specified in <i>mkfile</i> to control the
update (usually by compilation) of <i>targets</i> (usually files) from
the source files upon which they depend. The <i>mkfile</i> (default <tt><font size=+1>mkfile</font></tt>)
contains a <i>rule</i> for each target that identifies the files and
other targets upon which it depends and an <a href="../man1/sh.html"><i>sh</i>(1)</a> script, a
<i>recipe</i>, to update the target. The script is run if the target
does not exist or if it is older than any of the files it depends
on. <i>Mkfile</i> may also contain <i>meta-rules</i> that define actions for
updating implicit targets. If no <i>target</i> is specified, the target
of the first rule (not meta-rule) in <i>mkfile</i> is updated.
<table border=0 cellpadding=0 cellspacing=0><tr height=5><td></table>
The environment variable <tt><font size=+1>$NPROC</font></tt> determines how many targets may
be updated simultaneously; Some operating systems, e.g., Plan
9, set <tt><font size=+1>$NPROC</font></tt> automatically to the number of CPUs on the current
machine.
<table border=0 cellpadding=0 cellspacing=0><tr height=5><td></table>
Options are:<br>
<tt><font size=+1>−a</font></tt> Assume all targets to be out of date. Thus, everything is updated.<br>
<tt><font size=+1>−d</font></tt>[<tt><font size=+1>egp</font></tt>] Produce debugging output (<tt><font size=+1>p</font></tt> is for parsing, <tt><font size=+1>g</font></tt> for graph
building, <tt><font size=+1>e</font></tt> for execution).<br>
<tt><font size=+1>−e</font></tt> Explain why each target is made.<br>
<tt><font size=+1>−i</font></tt> Force any missing intermediate targets to be made.<br>
<tt><font size=+1>−k</font></tt> Do as much work as possible in the face of errors.<br>
<tt><font size=+1>−n</font></tt> Print, but do not execute, the commands needed to update the
targets.<br>
<tt><font size=+1>−s</font></tt> Make the command line arguments sequentially rather than in
parallel.<br>
<tt><font size=+1>−t</font></tt> Touch (update the modified date of) file targets, without executing
any recipes.<br>
<tt><font size=+1>−w</font></tt><i>target1</i><tt><font size=+1>,</font></tt><i>target2,...<br>
</i>
<table border=0 cellpadding=0 cellspacing=0><tr height=2><td><tr><td width=20><td>
<table border=0 cellpadding=0 cellspacing=0><tr height=2><td><tr><td width=20><td>
Pretend the modify time for each <i>target</i> is the current time; useful
in conjunction with <tt><font size=+1>−n</font></tt> to learn what updates would be triggered
by modifying the <i>targets</i>.<br>
</table>
</table>
<p><font size=+1><b>The <tt><font size=+1>mkfile </font></tt></b></font><br>
A <i>mkfile</i> consists of <i>assignments</i> (described under ‘Environment’)
and <i>rules</i>. A rule contains <i>targets</i> and a <i>tail</i>. A target is a literal
string and is normally a file name. The tail contains zero or
more <i>prerequisites</i> and an optional <i>recipe</i>, which is an <tt><font size=+1>shell</font></tt> script.
Each line of the recipe must begin with white space. A rule
takes the form<br>
<table border=0 cellpadding=0 cellspacing=0><tr height=2><td><tr><td width=20><td>
<tt><font size=+1>target: prereq1 prereq2<br>
</font></tt>
<table border=0 cellpadding=0 cellspacing=0><tr height=2><td><tr><td width=20><td>
<i>recipe using</i> <tt><font size=+1>prereq1, prereq2</font></tt> <i>to build</i> <tt><font size=+1>target<br>
<table border=0 cellpadding=0 cellspacing=0><tr height=5><td></table>
</font></tt>
</table>
</table>
When the recipe is executed, the first character on every line
is elided.
<table border=0 cellpadding=0 cellspacing=0><tr height=5><td></table>
After the colon on the target line, a rule may specify <i>attributes</i>,
described below.
<table border=0 cellpadding=0 cellspacing=0><tr height=5><td></table>
A <i>meta-rule</i> has a target of the form <i>A</i><tt><font size=+1>%</font></tt><i>B</i> where <i>A</i> and <i>B</i> are (possibly
empty) strings. A meta-rule acts as a rule for any potential target
whose name matches <i>A</i><tt><font size=+1>%</font></tt><i>B</i> with <tt><font size=+1>%</font></tt> replaced by an arbitrary string,
called the <i>stem</i>. In interpreting a meta-rule, the stem is substituted
for all occurrences of <tt><font size=+1>%</font></tt> in the prerequisite
names. In the recipe of a meta-rule, the environment variable
<tt><font size=+1>$stem</font></tt> contains the string matched by the <tt><font size=+1>%</font></tt>. For example, a meta-rule
to compile a C program using <a href="../man1/9c.html"><i>9c</i>(1)</a> might be:<br>
<table border=0 cellpadding=0 cellspacing=0><tr height=2><td><tr><td width=20><td>
<tt><font size=+1>%: %.c<br>
<table border=0 cellpadding=0 cellspacing=0><tr height=2><td><tr><td width=20><td>
9c −c $stem.c<br>
9l −o $stem $stem.o<br>
<table border=0 cellpadding=0 cellspacing=0><tr height=5><td></table>
</table>
</font></tt>
<table border=0 cellpadding=0 cellspacing=0><tr height=2><td><tr><td width=20><td>
</table>
</table>
Meta-rules may contain an ampersand <tt><font size=+1>&</font></tt> rather than a percent sign
<tt><font size=+1>%</font></tt>. A <tt><font size=+1>%</font></tt> matches a maximal length string of any characters; an <tt><font size=+1>&</font></tt>
matches a maximal length string of any characters except period
or slash.
<table border=0 cellpadding=0 cellspacing=0><tr height=5><td></table>
The text of the <i>mkfile</i> is processed as follows. Lines beginning
with <tt><font size=+1><</font></tt> followed by a file name are replaced by the contents of
the named file. Lines beginning with <tt><font size=+1><|</font></tt> followed by a file name
are replaced by the output of the execution of the named file.
Blank lines and comments, which run from unquoted <tt><font size=+1>#</font></tt> characters
to the following newline, are deleted. The character sequence
backslash-newline is deleted, so long lines in <i>mkfile</i> may be folded.
Non-recipe lines are processed by substituting for <tt><font size=+1>`{</font></tt><i>command</i><tt><font size=+1>}</font></tt>
the output of the <i>command</i> when run by <i>sh</i>. References to variables
are replaced by the variables’ values. Special
characters may be quoted using single quotes <tt><font size=+1>''</font></tt> as in <a href="../man1/sh.html"><i>sh</i>(1)</a>.
<table border=0 cellpadding=0 cellspacing=0><tr height=5><td></table>
Assignments and rules are distinguished by the first unquoted
occurrence of <tt><font size=+1>:</font></tt> (rule) or <tt><font size=+1>=</font></tt> (assignment).
<table border=0 cellpadding=0 cellspacing=0><tr height=5><td></table>
A later rule may modify or override an existing rule under the
following conditions:<br>
– If the targets of the rules exactly match and one rule contains
only a prerequisite clause and no recipe, the clause is added
to the prerequisites of the other rule. If either or both targets
are virtual, the recipe is always executed.<br>
– If the targets of the rules match exactly and the prerequisites
do not match and both rules contain recipes, <i>mk</i> reports an “ambiguous
recipe” error.<br>
– If the target and prerequisites of both rules match exactly, the
second rule overrides the first.<br>
<p><font size=+1><b>Environment </b></font><br>
Rules may make use of shell environment variables. A legal reference
of the form <tt><font size=+1>$OBJ</font></tt> or <tt><font size=+1>${name}</font></tt> is expanded as in <a href="../man1/sh.html"><i>sh</i>(1)</a>. A reference
of the form <tt><font size=+1>${name:</font></tt><i>A</i><tt><font size=+1>%</font></tt><i>B</i><tt><font size=+1>=</font></tt><i>C</i><tt><font size=+1>%</font></tt><i>D</i><tt><font size=+1>}</font></tt>, where <i>A, B, C, D</i> are (possibly empty)
strings, has the value formed by expanding <tt><font size=+1>$name</font></tt> and substituting
<i>C</i> for <i>A</i> and <i>D</i> for <i>B</i> in each word in
<tt><font size=+1>$name</font></tt> that matches pattern <i>A</i><tt><font size=+1>%</font></tt><i>B</i>.
<table border=0 cellpadding=0 cellspacing=0><tr height=5><td></table>
Variables can be set by assignments of the form<br>
<table border=0 cellpadding=0 cellspacing=0><tr height=2><td><tr><td width=20><td>
<i>var</i><tt><font size=+1>=</font></tt>[<i>attr</i><tt><font size=+1>=</font></tt>]<i>value<br>
</i>
</table>
Blanks in the <i>value</i> break it into words. Such variables are exported
to the environment of recipes as they are executed, unless <tt><font size=+1>U</font></tt>,
the only legal attribute <i>attr</i>, is present. The initial value of
a variable is taken from (in increasing order of precedence) the
default values below, <i>mk’s</i> environment, the <i>mkfiles</i>, and any
command line assignment as an argument to <i>mk</i>. A variable assignment
argument overrides the first (but not any subsequent) assignment
to that variable.
<table border=0 cellpadding=0 cellspacing=0><tr height=5><td></table>
The variable <tt><font size=+1>MKFLAGS</font></tt> contains all the option arguments (arguments
starting with <tt><font size=+1>−</font></tt> or containing <tt><font size=+1>=</font></tt>) and <tt><font size=+1>MKARGS</font></tt> contains all the targets
in the call to <i>mk</i>.
<table border=0 cellpadding=0 cellspacing=0><tr height=5><td></table>
The variable <tt><font size=+1>MKSHELL</font></tt> contains the shell command line <i>mk</i> uses to
run recipes. If the first word of the command ends in <tt><font size=+1>rc</font></tt> or <tt><font size=+1>rcsh</font></tt>,
<i>mk</i> uses <a href="../man1/rc.html"><i>rc</i>(1)</a>’s quoting rules; otherwise it uses <a href="../man1/sh.html"><i>sh</i>(1)</a>’s. The
<tt><font size=+1>MKSHELL</font></tt> variable is consulted when the mkfile is read, not when
it is executed, so that different shells can be used within
a single mkfile:<br>
<table border=0 cellpadding=0 cellspacing=0><tr height=2><td><tr><td width=20><td>
<tt><font size=+1>MKSHELL=$PLAN9/bin/rc<br>
use−rc:V:<br>
<table border=0 cellpadding=0 cellspacing=0><tr height=2><td><tr><td width=20><td>
for(i in a b c) echo $i<br>
</table>
MKSHELL=sh<br>
use−sh:V:<br>
<table border=0 cellpadding=0 cellspacing=0><tr height=2><td><tr><td width=20><td>
for i in a b c; do echo $i; done<br>
<table border=0 cellpadding=0 cellspacing=0><tr height=5><td></table>
</table>
</font></tt>
<table border=0 cellpadding=0 cellspacing=0><tr height=2><td><tr><td width=20><td>
</table>
</table>
Mkfiles included via <tt><font size=+1><</font></tt> or <tt><font size=+1><|</font></tt> (<i>q.v.</i>) see their own private copy of
<tt><font size=+1>MKSHELL</font></tt>, which always starts set to <tt><font size=+1>sh .
<table border=0 cellpadding=0 cellspacing=0><tr height=5><td></table>
</font></tt>
Dynamic information may be included in the mkfile by using a line
of the form<br>
<table border=0 cellpadding=0 cellspacing=0><tr height=2><td><tr><td width=20><td>
<|<i>command args
<table border=0 cellpadding=0 cellspacing=0><tr height=5><td></table>
</i>
</table>
This runs the command <i>command</i> with the given arguments <i>args</i> and
pipes its standard output to <i>mk</i> to be included as part of the
mkfile. For instance, the Inferno kernels use this technique to
run a shell command with an awk script and a configuration file
as arguments in order for the <i>awk</i> script to process the file
and output a set of variables and their values.<br>
<p><font size=+1><b>Execution </b></font><br>
<table border=0 cellpadding=0 cellspacing=0><tr height=5><td></table>
During execution, <i>mk</i> determines which targets must be updated,
and in what order, to build the <i>names</i> specified on the command
line. It then runs the associated recipes.
<table border=0 cellpadding=0 cellspacing=0><tr height=5><td></table>
A target is considered up to date if it has no prerequisites or
if all its prerequisites are up to date and it is newer than all
its prerequisites. Once the recipe for a target has executed,
the target is considered up to date.
<table border=0 cellpadding=0 cellspacing=0><tr height=5><td></table>
The date stamp used to determine if a target is up to date is
computed differently for different types of targets. If a target
is <i>virtual</i> (the target of a rule with the <tt><font size=+1>V</font></tt> attribute), its date
stamp is initially zero; when the target is updated the date stamp
is set to the most recent date stamp of its prerequisites. Otherwise,
if a
target does not exist as a file, its date stamp is set to the
most recent date stamp of its prerequisites, or zero if it has
no prerequisites. Otherwise, the target is the name of a file
and the target’s date stamp is always that file’s modification
date. The date stamp is computed when the target is needed in
the execution of
a rule; it is not a static value.
<table border=0 cellpadding=0 cellspacing=0><tr height=5><td></table>
Nonexistent targets that have prerequisites and are themselves
prerequisites are treated specially. Such a target <i>t</i> is given
the date stamp of its most recent prerequisite and if this causes
all the targets which have <i>t</i> as a prerequisite to be up to date,
<i>t</i> is considered up to date. Otherwise, <i>t</i> is made in the normal
fashion.
The <tt><font size=+1>−i</font></tt> flag overrides this special treatment.
<table border=0 cellpadding=0 cellspacing=0><tr height=5><td></table>
Files may be made in any order that respects the preceding restrictions.
<table border=0 cellpadding=0 cellspacing=0><tr height=5><td></table>
A recipe is executed by supplying the recipe as standard input
to the command <tt><font size=+1>/bin/sh</font></tt>. (Note that unlike <i>make</i>, <i>mk</i> feeds the entire
recipe to the shell rather than running each line of the recipe
separately.) The environment is augmented by the following variables:<br>
<tt><font size=+1>$alltarget<br>
</font></tt>
<table border=0 cellpadding=0 cellspacing=0><tr height=2><td><tr><td width=20><td>
<table border=0 cellpadding=0 cellspacing=0><tr height=2><td><tr><td width=20><td>
all the targets of this rule.<br>
</table>
</table>
<tt><font size=+1>$newprereq<br>
</font></tt>
<table border=0 cellpadding=0 cellspacing=0><tr height=2><td><tr><td width=20><td>
<table border=0 cellpadding=0 cellspacing=0><tr height=2><td><tr><td width=20><td>
the prerequisites that caused this rule to execute.<br>
</table>
</table>
<tt><font size=+1>$newmember<br>
</font></tt>
<table border=0 cellpadding=0 cellspacing=0><tr height=2><td><tr><td width=20><td>
<table border=0 cellpadding=0 cellspacing=0><tr height=2><td><tr><td width=20><td>
the prerequisites that are members of an aggregate that caused
this rule to execute. When the prerequisites of a rule are members
of an aggregate, <tt><font size=+1>$newprereq</font></tt> contains the name of the aggregate
and out of date members, while <tt><font size=+1>$newmember</font></tt> contains only the name
of the members.
</table>
</table>
<tt><font size=+1>$nproc</font></tt> the process slot for this recipe. It satisfies 0≤<tt><font size=+1>$nproc</font></tt><<tt><font size=+1>$NPROC</font></tt>.<br>
<tt><font size=+1>$pid</font></tt> the process id for the <i>mk</i> executing the recipe.<br>
<tt><font size=+1>$prereq</font></tt> all the prerequisites for this rule.<br>
<tt><font size=+1>$stem</font></tt> if this is a meta-rule, <tt><font size=+1>$stem</font></tt> is the string that matched
<tt><font size=+1>%</font></tt> or <tt><font size=+1>&</font></tt>. Otherwise, it is empty. For regular expression meta-rules
(see below), the variables <tt><font size=+1>stem0</font></tt>, ..., <tt><font size=+1>stem9</font></tt> are set to the corresponding
subexpressions.<br>
<tt><font size=+1>$target</font></tt> the targets for this rule that need to be remade.
<table border=0 cellpadding=0 cellspacing=0><tr height=5><td></table>
These variables are available only during the execution of a recipe,
not while evaluating the <i>mkfile</i>.
<table border=0 cellpadding=0 cellspacing=0><tr height=5><td></table>
Unless the rule has the <tt><font size=+1>Q</font></tt> attribute, the recipe is printed prior
to execution with recognizable environment variables expanded.
Commands returning error status cause <i>mk</i> to terminate.
<table border=0 cellpadding=0 cellspacing=0><tr height=5><td></table>
Recipes and backquoted <tt><font size=+1>rc</font></tt> commands in places such as assignments
execute in a copy of <i>mk’s</i> environment; changes they make to environment
variables are not visible from <i>mk</i>.
<table border=0 cellpadding=0 cellspacing=0><tr height=5><td></table>
Variable substitution in a rule is done when the rule is read;
variable substitution in the recipe is done when the recipe is
executed. For example:<br>
<table border=0 cellpadding=0 cellspacing=0><tr height=2><td><tr><td width=20><td>
<tt><font size=+1>bar=a.c<br>
foo: $bar<br>
<table border=0 cellpadding=0 cellspacing=0><tr height=2><td><tr><td width=20><td>
$CC −o foo $bar<br>
</table>
bar=b.c<br>
<table border=0 cellpadding=0 cellspacing=0><tr height=5><td></table>
</font></tt>
</table>
will compile <tt><font size=+1>b.c</font></tt> into <tt><font size=+1>foo</font></tt>, if <tt><font size=+1>a.c</font></tt> is newer than <tt><font size=+1>foo</font></tt>.<br>
<p><font size=+1><b>Aggregates </b></font><br>
Names of the form <i>a</i>(<i>b</i>) refer to member <i>b</i> of the aggregate <i>a</i>. Currently,
the only aggregates supported are <i>9ar</i> (see <a href="../man1/9c.html"><i>9c</i>(1)</a>) archives.<br>
<p><font size=+1><b>Attributes </b></font><br>
The colon separating the target from the prerequisites may be
immediately followed by <i>attributes</i> and another colon. The attributes
are:<br>
<tt><font size=+1>D</font></tt> If the recipe exits with a non-null status, the target is deleted.<br>
<tt><font size=+1>E</font></tt> Continue execution if the recipe draws errors.<br>
<tt><font size=+1>N</font></tt> If there is no recipe, the target has its time updated.<br>
<tt><font size=+1>n</font></tt> The rule is a meta-rule that cannot be a target of a virtual
rule. Only files match the pattern in the target.<br>
<tt><font size=+1>P</font></tt> The characters after the <tt><font size=+1>P</font></tt> until the terminating <tt><font size=+1>:</font></tt> are taken
as a program name. It will be invoked as <tt><font size=+1>sh −c prog 'arg1' 'arg2'</font></tt>
and should return a zero exit status if and only if arg1 is up
to date with respect to arg2. Date stamps are still propagated
in the normal way.<br>
<tt><font size=+1>Q</font></tt> The recipe is not printed prior to execution.<br>
<tt><font size=+1>R</font></tt> The rule is a meta-rule using regular expressions. In the rule,
<tt><font size=+1>%</font></tt> has no special meaning. The target is interpreted as a regular
expression as defined in <a href="../man7/regexp.html"><i>regexp</i>(7)</a>. The prerequisites may contain
references to subexpressions in form <tt><font size=+1>\</font></tt><i>n</i>, as in the substitute
command of <a href="../man1/sed.html"><i>sed</i>(1)</a>.<br>
<tt><font size=+1>U</font></tt> The targets are considered to have been updated even if the recipe
did not do so.<br>
<tt><font size=+1>V</font></tt> The targets of this rule are marked as virtual. They are distinct
from files of the same name.<br>
</table>
<p><font size=+1><b>EXAMPLES </b></font><br>
<table border=0 cellpadding=0 cellspacing=0><tr height=2><td><tr><td width=20><td>
A simple mkfile to compile a program:<br>
<table border=0 cellpadding=0 cellspacing=0><tr height=2><td><tr><td width=20><td>
<tt><font size=+1></$objtype/mkfile<br>
prog: a.$O b.$O c.$O<br>
<table border=0 cellpadding=0 cellspacing=0><tr height=2><td><tr><td width=20><td>
$LD $LDFLAGS −o $target $prereq<br>
</table>
%.$O: %.c<br>
<table border=0 cellpadding=0 cellspacing=0><tr height=2><td><tr><td width=20><td>
$CC $CFLAGS $stem.c<br>
<table border=0 cellpadding=0 cellspacing=0><tr height=5><td></table>
</table>
</font></tt>
<table border=0 cellpadding=0 cellspacing=0><tr height=2><td><tr><td width=20><td>
</table>
</table>
Override flag settings in the mkfile:<br>
<table border=0 cellpadding=0 cellspacing=0><tr height=2><td><tr><td width=20><td>
<tt><font size=+1>% mk target 'CFLAGS=−S −w'<br>
<table border=0 cellpadding=0 cellspacing=0><tr height=5><td></table>
</font></tt>
</table>
Maintain a library:<br>
<table border=0 cellpadding=0 cellspacing=0><tr height=2><td><tr><td width=20><td>
<tt><font size=+1>libc.a(%.$O):N: %.$O<br>
libc.a: libc.a(abs.$O) libc.a(access.$O) libc.a(alarm.$O) ...<br>
<table border=0 cellpadding=0 cellspacing=0><tr height=2><td><tr><td width=20><td>
ar r libc.a $newmember<br>
<table border=0 cellpadding=0 cellspacing=0><tr height=5><td></table>
</table>
</font></tt>
<table border=0 cellpadding=0 cellspacing=0><tr height=2><td><tr><td width=20><td>
</table>
</table>
String expression variables to derive names from a master list:<br>
<table border=0 cellpadding=0 cellspacing=0><tr height=2><td><tr><td width=20><td>
<tt><font size=+1>NAMES=alloc arc bquote builtins expand main match mk var word<br>
OBJ=${NAMES:%=%.$O}<br>
<table border=0 cellpadding=0 cellspacing=0><tr height=5><td></table>
</font></tt>
</table>
Regular expression meta-rules:<br>
<table border=0 cellpadding=0 cellspacing=0><tr height=2><td><tr><td width=20><td>
<tt><font size=+1>([^/]*)/(.*)\.$O:R: \1/\2.c<br>
<table border=0 cellpadding=0 cellspacing=0><tr height=2><td><tr><td width=20><td>
cd $stem1; $CC $CFLAGS $stem2.c<br>
<table border=0 cellpadding=0 cellspacing=0><tr height=5><td></table>
</table>
</font></tt>
<table border=0 cellpadding=0 cellspacing=0><tr height=2><td><tr><td width=20><td>
</table>
</table>
A correct way to deal with <a href="../man1/yacc.html"><i>yacc</i>(1)</a> grammars. The file <tt><font size=+1>lex.c</font></tt> includes
the file <tt><font size=+1>x.tab.h</font></tt> rather than <tt><font size=+1>y.tab.h</font></tt> in order to reflect changes
in content, not just modification time.<br>
<table border=0 cellpadding=0 cellspacing=0><tr height=2><td><tr><td width=20><td>
<tt><font size=+1>lex.$O: x.tab.h<br>
x.tab.h: y.tab.h<br>
<table border=0 cellpadding=0 cellspacing=0><tr height=2><td><tr><td width=20><td>
cmp −s x.tab.h y.tab.h || cp y.tab.h x.tab.h<br>
</table>
y.tab.c y.tab.h: gram.y<br>
<table border=0 cellpadding=0 cellspacing=0><tr height=2><td><tr><td width=20><td>
$YACC −d gram.y<br>
<table border=0 cellpadding=0 cellspacing=0><tr height=5><td></table>
</table>
</font></tt>
<table border=0 cellpadding=0 cellspacing=0><tr height=2><td><tr><td width=20><td>
</table>
</table>
The above example could also use the <tt><font size=+1>P</font></tt> attribute for the <tt><font size=+1>x.tab.h</font></tt>
rule:<br>
<table border=0 cellpadding=0 cellspacing=0><tr height=2><td><tr><td width=20><td>
<tt><font size=+1>x.tab.h:Pcmp −s: y.tab.h<br>
<table border=0 cellpadding=0 cellspacing=0><tr height=2><td><tr><td width=20><td>
cp y.tab.h x.tab.h<br>
</table>
</font></tt>
</table>
</table>
<p><font size=+1><b>SOURCE </b></font><br>
<table border=0 cellpadding=0 cellspacing=0><tr height=2><td><tr><td width=20><td>
<tt><font size=+1>/usr/local/plan9/src/cmd/mk<br>
</font></tt>
</table>
<p><font size=+1><b>SEE ALSO </b></font><br>
<table border=0 cellpadding=0 cellspacing=0><tr height=2><td><tr><td width=20><td>
<a href="../man1/sh.html"><i>sh</i>(1)</a>, <a href="../man7/regexp.html"><i>regexp</i>(7)</a>
<table border=0 cellpadding=0 cellspacing=0><tr height=5><td></table>
A. Hume, “Mk: a Successor to Make” (Tenth Edition Research Unix
Manuals).
<table border=0 cellpadding=0 cellspacing=0><tr height=5><td></table>
Andrew G. Hume and Bob Flandrena, “Maintaining Files on Plan 9
with Mk”. DOCPREFIX/doc/mk.pdf<br>
</table>
<p><font size=+1><b>HISTORY </b></font><br>
<table border=0 cellpadding=0 cellspacing=0><tr height=2><td><tr><td width=20><td>
Andrew Hume wrote <i>mk</i> for Tenth Edition Research Unix. It was later
ported to Plan 9. This software is a port of the Plan 9 version
back to Unix.<br>
</table>
<p><font size=+1><b>BUGS </b></font><br>
<table border=0 cellpadding=0 cellspacing=0><tr height=2><td><tr><td width=20><td>
Identical recipes for regular expression meta-rules only have
one target.
<table border=0 cellpadding=0 cellspacing=0><tr height=5><td></table>
Seemingly appropriate input like <tt><font size=+1>CFLAGS=−DHZ=60</font></tt> is parsed as an
erroneous attribute; correct it by inserting a space after the
first <tt><font size=+1>=</font></tt>.
<table border=0 cellpadding=0 cellspacing=0><tr height=5><td></table>
The recipes printed by <i>mk</i> before being passed to the shell for
execution are sometimes erroneously expanded for printing. Don’t
trust what’s printed; rely on what the shell does.<br>
</table>
<td width=20>
<tr height=20><td>
</table>
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