refcards.html

Shall高级编程

><TR
><TD
ALIGN="LEFT"
VALIGN="TOP"
><TT
CLASS="OPTION"
>-L</TT
></TD
><TD
ALIGN="LEFT"
VALIGN="TOP"
>File is a <I
CLASS="FIRSTTERM"
>symbolic link</I
></TD
><TD
ALIGN="LEFT"
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>&nbsp;</TD
><TD
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VALIGN="TOP"
><TT
CLASS="OPTION"
>-x</TT
></TD
><TD
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>File has <I
CLASS="FIRSTTERM"
>execute</I
>
	        permission</TD
></TR
><TR
><TD
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VALIGN="TOP"
><TT
CLASS="OPTION"
>-b</TT
></TD
><TD
ALIGN="LEFT"
VALIGN="TOP"
>File is a <I
CLASS="FIRSTTERM"
>block device</I
></TD
><TD
>&nbsp;</TD
><TD
>&nbsp;</TD
><TD
>&nbsp;</TD
></TR
><TR
><TD
ALIGN="LEFT"
VALIGN="TOP"
><TT
CLASS="OPTION"
>-c</TT
></TD
><TD
ALIGN="LEFT"
VALIGN="TOP"
>File is a <I
CLASS="FIRSTTERM"
>character device</I
></TD
><TD
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>&nbsp;</TD
><TD
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VALIGN="TOP"
><TT
CLASS="OPTION"
>-g</TT
></TD
><TD
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><I
CLASS="FIRSTTERM"
>sgid</I
> flag set</TD
></TR
><TR
><TD
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VALIGN="TOP"
><TT
CLASS="OPTION"
>-p</TT
></TD
><TD
ALIGN="LEFT"
VALIGN="TOP"
>File is a <A
HREF="special-chars.html#PIPEREF"
>pipe</A
></TD
><TD
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VALIGN="TOP"
>&nbsp;</TD
><TD
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VALIGN="TOP"
><TT
CLASS="OPTION"
>-u</TT
></TD
><TD
ALIGN="LEFT"
VALIGN="TOP"
><I
CLASS="FIRSTTERM"
>suid</I
> flag set</TD
></TR
><TR
><TD
ALIGN="LEFT"
VALIGN="TOP"
><TT
CLASS="OPTION"
>-S</TT
></TD
><TD
ALIGN="LEFT"
VALIGN="TOP"
>File is a <A
HREF="devproc.html#SOCKETREF"
>socket</A
></TD
><TD
ALIGN="LEFT"
VALIGN="TOP"
>&nbsp;</TD
><TD
ALIGN="LEFT"
VALIGN="TOP"
><TT
CLASS="OPTION"
>-k</TT
></TD
><TD
ALIGN="LEFT"
VALIGN="TOP"
><SPAN
CLASS="QUOTE"
>"sticky bit"</SPAN
> set</TD
></TR
><TR
><TD
ALIGN="LEFT"
VALIGN="TOP"
><TT
CLASS="OPTION"
>-t</TT
></TD
><TD
ALIGN="LEFT"
VALIGN="TOP"
>File is associated with a
	        <I
CLASS="FIRSTTERM"
>terminal</I
></TD
><TD
>&nbsp;</TD
><TD
>&nbsp;</TD
><TD
>&nbsp;</TD
></TR
><TR
><TD
ALIGN="LEFT"
VALIGN="TOP"
>&nbsp;</TD
><TD
>&nbsp;</TD
><TD
>&nbsp;</TD
><TD
>&nbsp;</TD
><TD
>&nbsp;</TD
></TR
><TR
><TD
ALIGN="LEFT"
VALIGN="TOP"
><TT
CLASS="OPTION"
>-N</TT
></TD
><TD
ALIGN="LEFT"
VALIGN="TOP"
>File modified since it was last read</TD
><TD
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VALIGN="TOP"
>&nbsp;</TD
><TD
ALIGN="LEFT"
VALIGN="TOP"
><TT
CLASS="OPTION"
>F1 -nt F2</TT
></TD
><TD
ALIGN="LEFT"
VALIGN="TOP"
>File F1 is <SPAN
CLASS="emphasis"
><I
CLASS="EMPHASIS"
>newer</I
></SPAN
> than F2 *</TD
></TR
><TR
><TD
ALIGN="LEFT"
VALIGN="TOP"
><TT
CLASS="OPTION"
>-O</TT
></TD
><TD
ALIGN="LEFT"
VALIGN="TOP"
>You own the file</TD
><TD
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VALIGN="TOP"
>&nbsp;</TD
><TD
ALIGN="LEFT"
VALIGN="TOP"
><TT
CLASS="OPTION"
>F1 -ot F2</TT
></TD
><TD
ALIGN="LEFT"
VALIGN="TOP"
>File F1 is <SPAN
CLASS="emphasis"
><I
CLASS="EMPHASIS"
>older</I
></SPAN
> than F2 *</TD
></TR
><TR
><TD
ALIGN="LEFT"
VALIGN="TOP"
><TT
CLASS="OPTION"
>-G</TT
></TD
><TD
ALIGN="LEFT"
VALIGN="TOP"
><I
CLASS="FIRSTTERM"
>Group id</I
> of file same as
	        yours</TD
><TD
ALIGN="LEFT"
VALIGN="TOP"
>&nbsp;</TD
><TD
ALIGN="LEFT"
VALIGN="TOP"
><TT
CLASS="OPTION"
>F1 -ef F2</TT
></TD
><TD
ALIGN="LEFT"
VALIGN="TOP"
>Files F1 and F2 are <I
CLASS="FIRSTTERM"
>hard links</I
>
	        to the same file *</TD
></TR
><TR
><TD
ALIGN="LEFT"
VALIGN="TOP"
>&nbsp;</TD
><TD
>&nbsp;</TD
><TD
>&nbsp;</TD
><TD
>&nbsp;</TD
><TD
>&nbsp;</TD
></TR
><TR
><TD
ALIGN="LEFT"
VALIGN="TOP"
><TT
CLASS="OPTION"
>!</TT
></TD
><TD
ALIGN="LEFT"
VALIGN="TOP"
><SPAN
CLASS="QUOTE"
>"NOT"</SPAN
> (reverses sense of above
	        tests)</TD
><TD
>&nbsp;</TD
><TD
>&nbsp;</TD
><TD
>&nbsp;</TD
></TR
></TBODY
></TABLE
><HR></DIV
><P
><B
CLASS="COMMAND"
>*</B
> <I
CLASS="FIRSTTERM"
>Binary</I
> operator
        (requires two operands).</P
><P
><A
NAME="PARSUBTAB"
></A
></P
><DIV
CLASS="TABLE"
><HR><A
NAME="AEN20641"
></A
><P
><B
>Table B-4. Parameter Substitution and Expansion</B
></P
><TABLE
BORDER="1"
CLASS="CALSTABLE"
><THEAD
><TR
><TH
ALIGN="LEFT"
VALIGN="TOP"
>Expression</TH
><TH
ALIGN="LEFT"
VALIGN="TOP"
>Meaning</TH
></TR
></THEAD
><TBODY
><TR
><TD
ALIGN="LEFT"
VALIGN="TOP"
><TT
CLASS="OPTION"
>${var}</TT
></TD
><TD
ALIGN="LEFT"
VALIGN="TOP"
>Value of <TT
CLASS="PARAMETER"
><I
>var</I
></TT
>, same as
	        <TT
CLASS="PARAMETER"
><I
>$var</I
></TT
></TD
></TR
><TR
><TD
ALIGN="LEFT"
VALIGN="TOP"
>&nbsp;</TD
><TD
ALIGN="LEFT"
VALIGN="TOP"
>&nbsp;</TD
></TR
><TR
><TD
ALIGN="LEFT"
VALIGN="TOP"
><TT
CLASS="OPTION"
>${var-DEFAULT}</TT
></TD
><TD
ALIGN="LEFT"
VALIGN="TOP"
>If <TT
CLASS="PARAMETER"
><I
>var</I
></TT
> not set, evaluate expression
	        as <TT
CLASS="PARAMETER"
><I
>$DEFAULT</I
></TT
> *</TD
></TR
><TR
><TD
ALIGN="LEFT"
VALIGN="TOP"
><TT
CLASS="OPTION"
>${var:-DEFAULT}</TT
></TD
><TD
ALIGN="LEFT"
VALIGN="TOP"
>If <TT
CLASS="PARAMETER"
><I
>var</I
></TT
> not set or is empty,
		evaluate expression as <TT
CLASS="PARAMETER"
><I
>$DEFAULT</I
></TT
>
		*</TD
></TR
><TR
><TD
ALIGN="LEFT"
VALIGN="TOP"
>&nbsp;</TD
><TD
ALIGN="LEFT"
VALIGN="TOP"
>&nbsp;</TD
></TR
><TR
><TD
ALIGN="LEFT"
VALIGN="TOP"
><TT
CLASS="OPTION"
>${var=DEFAULT}</TT
></TD
><TD
ALIGN="LEFT"
VALIGN="TOP"
>If <TT
CLASS="PARAMETER"
><I
>var</I
></TT
> not set, evaluate expression
	        as <TT
CLASS="PARAMETER"
><I
>$DEFAULT</I
></TT
> *</TD
></TR
><TR
><TD
ALIGN="LEFT"
VALIGN="TOP"
><TT
CLASS="OPTION"
>${var:=DEFAULT}</TT
></TD
><TD
ALIGN="LEFT"
VALIGN="TOP"
>If <TT
CLASS="PARAMETER"
><I
>var</I
></TT
> not set, evaluate expression
	        as <TT
CLASS="PARAMETER"
><I
>$DEFAULT</I
></TT
> *</TD
></TR
><TR
><TD
ALIGN="LEFT"
VALIGN="TOP"
>&nbsp;</TD
><TD
ALIGN="LEFT"
VALIGN="TOP"
>&nbsp;</TD
></TR
><TR
><TD
ALIGN="LEFT"
VALIGN="TOP"
><TT
CLASS="OPTION"
>${var+OTHER}</TT
></TD
><TD
ALIGN="LEFT"
VALIGN="TOP"
>If <TT
CLASS="PARAMETER"
><I
>var</I
></TT
> set, evaluate expression as
	        <TT
CLASS="PARAMETER"
><I
>$OTHER</I
></TT
>, otherwise as null string</TD
></TR
><TR
><TD
ALIGN="LEFT"
VALIGN="TOP"
><TT
CLASS="OPTION"
>${var:+OTHER}</TT
></TD
><TD
ALIGN="LEFT"
VALIGN="TOP"
>If <TT
CLASS="PARAMETER"
><I
>var</I
></TT
> set, evaluate expression as
	        <TT
CLASS="PARAMETER"
><I
>$OTHER</I
></TT
>, otherwise as null string</TD
></TR
><TR
><TD
ALIGN="LEFT"
VALIGN="TOP"
>&nbsp;</TD
><TD
ALIGN="LEFT"
VALIGN="TOP"
>&nbsp;</TD
></TR
><TR
><TD
ALIGN="LEFT"
VALIGN="TOP"
><TT
CLASS="OPTION"
>${var?ERR_MSG}</TT
></TD
><TD
ALIGN="LEFT"
VALIGN="TOP"
>If <TT
CLASS="PARAMETER"
><I
>var</I
></TT
> not set, print
	        <TT
CLASS="PARAMETER"
><I
>$ERR_MSG</I
></TT
> *</TD
></TR
><TR
><TD
ALIGN="LEFT"
VALIGN="TOP"
><TT
CLASS="OPTION"
>${var:?ERR_MSG}</TT
></TD
><TD
ALIGN="LEFT"
VALIGN="TOP"
>If <TT
CLASS="PARAMETER"
><I
>var</I
></TT
> not set, print
	        <TT
CLASS="PARAMETER"
><I
>$ERR_MSG</I
></TT
> *</TD
></TR
><TR
><TD
ALIGN="LEFT"
VALIGN="TOP"
>&nbsp;</TD
><TD
ALIGN="LEFT"
VALIGN="TOP"
>&nbsp;</TD
></TR
><TR
><TD
ALIGN="LEFT"
VALIGN="TOP"
><TT
CLASS="OPTION"
>${!varprefix*}</TT
></TD
><TD
ALIGN="LEFT"
VALIGN="TOP"
>Matches all previously declared variables beginning with
	        <TT
CLASS="PARAMETER"
><I
>varprefix</I
></TT
></TD
></TR
><TR
><TD
ALIGN="LEFT"
VALIGN="TOP"
><TT
CLASS="OPTION"
>${!varprefix@}</TT
></TD
><TD
ALIGN="LEFT"
VALIGN="TOP"
>Matches all previously declared variables beginning with
	        <TT
CLASS="PARAMETER"
><I
>varprefix</I
></TT
></TD
></TR
></TBODY
></TABLE
><HR></DIV
><P
><B
CLASS="COMMAND"
>*</B
> Of course if <TT
CLASS="PARAMETER"
><I
>var</I
></TT
>
        <SPAN
CLASS="emphasis"
><I
CLASS="EMPHASIS"
>is</I
></SPAN
> set, evaluate the expression as
	<TT
CLASS="PARAMETER"
><I
>$var</I
></TT
>.</P
><P
><A
NAME="STRINGOPSTAB"
></A
></P
><DIV
CLASS="TABLE"
><HR><A
NAME="AEN20735"
></A
><P
><B
>Table B-5. String Operations</B
></P
><TABLE
BORDER="1"
CLASS="CALSTABLE"
><THEAD
><TR
><TH
ALIGN="LEFT"
VALIGN="TOP"
>Expression</TH
><TH
ALIGN="LEFT"
VALIGN="TOP"
>Meaning</TH
></TR
></THEAD
><TBODY
><TR
><TD
ALIGN="LEFT"
VALIGN="TOP"
><TT
CLASS="OPTION"
>${#string}</TT
></TD
><TD
ALIGN="LEFT"
VALIGN="TOP"
>Length of <TT
CLASS="PARAMETER"
><I
>$string</I
></TT
></TD
></TR
><TR
><TD
ALIGN="LEFT"
VALIGN="TOP"
>&nbsp;</TD
><TD
ALIGN="LEFT"
VALIGN="TOP"
>&nbsp;</TD
></TR
><TR
><TD
ALIGN="LEFT"
VALIGN="TOP"
><TT
CLASS="OPTION"
>${string:position}</TT
></TD
><TD
ALIGN="LEFT"
VALIGN="TOP"
>Extract substring from <TT
CLASS="PARAMETER"
><I
>$string</I
></TT
>
		at <TT
CLASS="PARAMETER"
><I
>$position</I
></TT
></TD
></TR
><TR
><TD
ALIGN="LEFT"
VALIGN="TOP"
><TT
CLASS="OPTION"
>${string:position:length}</TT
></TD
><TD
ALIGN="LEFT"
VALIGN="TOP"
>Extract <TT
CLASS="PARAMETER"
><I
>$length</I
></TT
>
		characters substring from <TT
CLASS="PARAMETER"
><I
>$string</I
></TT
>
		at <TT
CLASS="PARAMETER"
><I
>$position</I
></TT
></TD
></TR
><TR
><TD
ALIGN="LEFT"
VALIGN="TOP"
>&nbsp;</TD
><TD
ALIGN="LEFT"
VALIGN="TOP"
>&nbsp;</TD
></TR
><TR
><TD
ALIGN="LEFT"
VALIGN="TOP"
><TT
CLASS="OPTION"
>${string#substring}</TT
></TD
><TD
ALIGN="LEFT"
VALIGN="TOP"
>Strip shortest match of
	      <TT
CLASS="PARAMETER"
><I
>$substring</I
></TT
> from front of
	      <TT
CLASS="PARAMETER"
><I
>$string</I
></TT
></TD
></TR
><TR
><TD
ALIGN="LEFT"
VALIGN="TOP"
><TT
CLASS="OPTION"
>${string##substring}</TT
></TD
><TD
ALIGN="LEFT"
VALIGN="TOP"
>Strip longest match of
	      <TT
CLASS="PARAMETER"
><I
>$substring</I
></TT
> from front of
	      <TT
CLASS="PARAMETER"
><I
>$string</I
></TT
></TD
></TR
><TR
><TD
ALIGN="LEFT"
VALIGN="TOP"
><TT
CLASS="OPTION"
>${string%substring}</TT
></TD
><TD
ALIGN="LEFT"
VALIGN="TOP"
>Strip shortest match of
	      <TT
CLASS="PARAMETER"
><I
>$substring</I
></TT
> from back of
	      <TT
CLASS="PARAMETER"
><I
>$string</I
></TT
></TD
></TR
><TR
><TD
ALIGN="LEFT"
VALIGN="TOP"
><TT
CLASS="OPTION"
>${string%%substring}</TT
></TD
><TD
ALIGN="LEFT"
VALIGN="TOP"
>Strip longest match of
	      <TT
CLASS="PARAMETER"
><I
>$substring</I
></TT
> from back of
	      <TT
CLASS="PARAMETER"
><I
>$string</I
></TT
></TD
></TR
><TR
><TD
ALIGN="LEFT"
VALIGN="TOP"
>&nbsp;</TD
><TD
ALIGN="LEFT"
VALIGN="TOP"
>&nbsp;</TD
></TR
><TR
><TD
ALIGN="LEFT"
VALIGN="TOP"
><TT
CLASS="OPTION"
>${string/substring/replacement}</TT
></TD
><TD
ALIGN="LEFT"
VALIGN="TOP"
>Replace first match of
	      <TT
CLASS="PARAMETER"
><I
>$substring</I
></TT
> with
	      <TT
CLASS="PARAMETER"