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<title>17.2 Filenames and devices</title>
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<h2>
<a name="1204466"> </a><font color="#003366" face="Verdana, Arial, Helvetica, sans-serif">17.2 Filenames and devices</font>
</h2><hr>
<p>
<a name="1204467"> </a><font size=2 face="Verdana, Arial, Helvetica, sans-serif">All devices in the system are accessed through named files, which are simple character strings. These filenames have two components:</font>
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<p> <font size=2 face="Verdana, Arial, Helvetica, sans-serif"><li ><a name="1204468"> </a>a device name, which specifies which device driver is called to operate on that device,</font></p>
<p> <font size=2 face="Verdana, Arial, Helvetica, sans-serif"><li ><a name="1204469"> </a>a qualifier, which can be used by the device driver to identify a file on that device.</font></p>
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<p>
<a name="1204470"> </a><font size=2 face="Verdana, Arial, Helvetica, sans-serif">These two components are separated by a colon, for example:</font>
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<p> <font size=2 face="Verdana, Arial, Helvetica, sans-serif"><li ><a name="1204471"> </a><font size=2 face=Courier><strong>disk:/a/b/x.c</strong></font> specifies the file <font size=2 face=Courier><strong>/a/b/x.c</strong></font> on the disk device.</font></p>
<p> <font size=2 face="Verdana, Arial, Helvetica, sans-serif"><li ><a name="1204472"> </a><font size=2 face=Courier><strong>uart:1</strong></font> uses the UART device driver, and refers to the second device managed by that driver.</font></p>
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<p>
<a name="1204473"> </a><font size=2 face="Verdana, Arial, Helvetica, sans-serif">Omitting one or other (but not both) of the component of the filename is possible:</font>
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<p> <font size=2 face="Verdana, Arial, Helvetica, sans-serif"><li ><a name="1204474"> </a><font size=2 face=Courier><strong>LED:</strong></font> refers to a device which does not have any qualifiers (the colon must still be specified).</font></p>
<p> <font size=2 face="Verdana, Arial, Helvetica, sans-serif"><li ><a name="1204477"> </a><font size=2 face=Courier><strong>/fred/jim/john.txt</strong></font> refers to a file on the default device (see <a href="posix5.htm#1204491"><font color="#0000ff" face="Verdana, Arial, Helvetica, sans-serif"><i>Section⌨️ 快捷键说明
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