244 lines
3.4 KiB
HTML
244 lines
3.4 KiB
HTML
<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.0 Transitional//EN">
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<HTML
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>A Sed and Awk Micro-Primer</TITLE
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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="Advanced Bash-Scripting Guide"
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HREF="index.html"><LINK
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TITLE="Reference Cards"
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HREF="refcards.html"><LINK
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REL="NEXT"
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TITLE="Sed"
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HREF="x23170.html"></HEAD
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><TH
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COLSPAN="3"
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ALIGN="center"
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>Advanced Bash-Scripting Guide: </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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WIDTH="100%"></DIV
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><DIV
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CLASS="APPENDIX"
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><H1
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><A
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NAME="SEDAWK"
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></A
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>Appendix C. A Sed and Awk Micro-Primer</H1
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><DIV
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CLASS="TOC"
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><DL
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><DT
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><B
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>Table of Contents</B
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></DT
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><DT
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>C.1. <A
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HREF="x23170.html"
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>Sed</A
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></DT
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><DT
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>C.2. <A
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HREF="awk.html"
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>Awk</A
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></DT
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></DL
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></DIV
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><P
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><A
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NAME="SEDREF"
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></A
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></P
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><P
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>This is a very brief introduction to the <B
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CLASS="COMMAND"
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>sed</B
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>
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and <B
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CLASS="COMMAND"
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>awk</B
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> text processing utilities. We will
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deal with only a few basic commands here, but that will suffice
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for understanding simple sed and awk constructs within shell
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scripts.</P
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><P
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><B
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CLASS="COMMAND"
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>sed</B
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>: a non-interactive
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text file editor</P
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><P
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><B
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CLASS="COMMAND"
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>awk</B
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>: a field-oriented pattern processing
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language with a <B
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CLASS="COMMAND"
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>C</B
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>-style syntax</P
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><P
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>For all their differences, the two utilities share a similar
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invocation syntax, use <A
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HREF="regexp.html#REGEXREF"
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>regular
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expressions </A
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>, read input by default
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from <TT
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CLASS="FILENAME"
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>stdin</TT
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>, and output to
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<TT
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CLASS="FILENAME"
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>stdout</TT
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>. These are well-behaved UNIX tools,
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and they work together well. The output from one can be piped
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to the other, and their combined capabilities give shell scripts
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some of the power of <A
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HREF="wrapper.html#PERLREF"
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>Perl</A
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>.</P
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><DIV
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CLASS="NOTE"
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><P
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></P
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><TABLE
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CLASS="NOTE"
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><TR
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><TD
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WIDTH="25"
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VALIGN="TOP"
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><IMG
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SRC="../images/note.gif"
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HSPACE="5"
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ALT="Note"></TD
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><TD
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ALIGN="LEFT"
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VALIGN="TOP"
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><P
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>One important difference between the utilities is
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that while shell scripts can easily pass arguments to sed, it
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is more cumbersome for awk (see <A
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HREF="wrapper.html#COLTOTALER"
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>Example 36-5</A
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>
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and <A
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HREF="ivr.html#COLTOTALER2"
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>Example 28-2</A
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>).
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</P
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></TD
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></TR
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></TABLE
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></DIV
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></DIV
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><DIV
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CLASS="NAVFOOTER"
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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="refcards.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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VALIGN="top"
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HREF="index.html"
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>Home</A
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></TD
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><TD
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ALIGN="right"
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VALIGN="top"
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><A
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HREF="x23170.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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>Reference Cards</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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> </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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>Sed</TD
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> |