182 lines
2.9 KiB
HTML
182 lines
2.9 KiB
HTML
<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.0 Transitional//EN">
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<HTML
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><HEAD
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><TITLE
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>Summary</TITLE
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><META
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NAME="GENERATOR"
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CONTENT="Modular DocBook HTML Stylesheet Version 1.7"><LINK
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REL="HOME"
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TITLE="Bash Guide for Beginners"
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HREF="index.html"><LINK
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REL="UP"
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TITLE="Repetitive tasks"
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HREF="chap_09.html"><LINK
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REL="PREVIOUS"
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TITLE="The shift built-in"
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HREF="sect_09_07.html"><LINK
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REL="NEXT"
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TITLE="Exercises"
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HREF="sect_09_09.html"></HEAD
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><BODY
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CLASS="sect1"
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BGCOLOR="#FFFFFF"
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TEXT="#000000"
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LINK="#0000FF"
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VLINK="#840084"
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ALINK="#0000FF"
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><DIV
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CLASS="NAVHEADER"
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><TABLE
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SUMMARY="Header navigation table"
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WIDTH="100%"
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BORDER="0"
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CELLPADDING="0"
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CELLSPACING="0"
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><TR
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><TH
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COLSPAN="3"
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ALIGN="center"
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>Bash Guide for Beginners</TH
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></TR
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><TR
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><TD
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WIDTH="10%"
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ALIGN="left"
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VALIGN="bottom"
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><A
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HREF="sect_09_07.html"
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ACCESSKEY="P"
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>Prev</A
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></TD
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><TD
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WIDTH="80%"
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ALIGN="center"
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VALIGN="bottom"
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>Chapter 9. Repetitive tasks</TD
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><TD
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WIDTH="10%"
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ALIGN="right"
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VALIGN="bottom"
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><A
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HREF="sect_09_09.html"
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ACCESSKEY="N"
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>Next</A
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></TD
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></TR
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></TABLE
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><HR
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ALIGN="LEFT"
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WIDTH="100%"></DIV
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><DIV
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CLASS="sect1"
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><H1
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CLASS="sect1"
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><A
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NAME="sect_09_08"
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></A
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>9.8. Summary</H1
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><P
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>In this chapter, we discussed how repetitive commands can be incorporated in loop constructs. Most common loops are built using the <B
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CLASS="command"
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>for</B
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>, <B
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CLASS="command"
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>while</B
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> or <B
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CLASS="command"
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>until</B
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> statements, or a combination of these commands. The <B
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CLASS="command"
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>for</B
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> loop executes a task a defined number of times. If you don't know how many times a command should execute, use either <B
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CLASS="command"
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>until</B
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> or <B
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CLASS="command"
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>while</B
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> to specify when the loop should end.</P
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><P
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>Loops can be interrupted or reiterated using the <B
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CLASS="command"
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>break</B
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> and <B
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CLASS="command"
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>continue</B
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> statements.</P
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><P
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>A file can be used as input for a loop using the input redirection operator, loops can also read output from commands that is fed into the loop using a pipe.</P
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><P
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>The <B
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CLASS="command"
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>select</B
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> construct is used for printing menus in interactive scripts. Looping through the command line arguments to a script can be done using the <B
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CLASS="command"
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>shift</B
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> statement.</P
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></DIV
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><DIV
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CLASS="NAVFOOTER"
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><HR
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ALIGN="LEFT"
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WIDTH="100%"><TABLE
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SUMMARY="Footer navigation table"
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WIDTH="100%"
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BORDER="0"
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CELLPADDING="0"
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CELLSPACING="0"
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><TR
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><TD
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WIDTH="33%"
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ALIGN="left"
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VALIGN="top"
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><A
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HREF="sect_09_07.html"
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ACCESSKEY="P"
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>Prev</A
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></TD
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><TD
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WIDTH="34%"
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ALIGN="center"
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VALIGN="top"
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><A
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HREF="index.html"
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ACCESSKEY="H"
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>Home</A
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></TD
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><TD
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WIDTH="33%"
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ALIGN="right"
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VALIGN="top"
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><A
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HREF="sect_09_09.html"
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ACCESSKEY="N"
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>Next</A
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></TD
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></TR
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><TR
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><TD
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WIDTH="33%"
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ALIGN="left"
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VALIGN="top"
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>The shift built-in</TD
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><TD
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WIDTH="34%"
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ALIGN="center"
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VALIGN="top"
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><A
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HREF="chap_09.html"
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ACCESSKEY="U"
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>Up</A
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></TD
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><TD
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WIDTH="33%"
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ALIGN="right"
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VALIGN="top"
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>Exercises</TD
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></TR
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></TABLE
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></DIV
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></BODY
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></HTML
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> |