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<HTML><!--Distributed by F --><HEAD><TITLE>[Chapter 35] 35.7 offset: Indent Text </TITLE><METANAME="DC.title"CONTENT="UNIX Power Tools"><METANAME="DC.creator"CONTENT="Jerry Peek, Tim O'Reilly & Mike Loukides"><METANAME="DC.publisher"CONTENT="O'Reilly & Associates, Inc."><METANAME="DC.date"CONTENT="1998-08-04T21:48:04Z"><METANAME="DC.type"CONTENT="Text.Monograph"><METANAME="DC.format"CONTENT="text/html"SCHEME="MIME"><METANAME="DC.source"CONTENT="1-56592-260-3"SCHEME="ISBN"><METANAME="DC.language"CONTENT="en-US"><METANAME="generator"CONTENT="Jade 1.1/O'Reilly DocBook 3.0 to HTML 4.0"><LINKREV="made"HREF="mailto:online-books@oreilly.com"TITLE="Online Books Comments"><LINKREL="up"HREF="ch35_01.htm"TITLE="35. You Can't Quite Call This Editing"><LINKREL="prev"HREF="ch35_06.htm"TITLE="35.6 Low-Level File Butchery with dd "><LINKREL="next"HREF="ch35_08.htm"TITLE="35.8 Centering Lines in a File "></HEAD><BODYBGCOLOR="#FFFFFF"TEXT="#000000"><DIVCLASS="htmlnav"><H1><IMGSRC="gifs/smbanner.gif"ALT="UNIX Power Tools"USEMAP="#srchmap"BORDER="0"></H1><MAPNAME="srchmap"><AREASHAPE="RECT"COORDS="0,0,466,58"HREF="index.htm"ALT="UNIX Power Tools"><AREASHAPE="RECT"COORDS="467,0,514,18"HREF="jobjects/fsearch.htm"ALT="Search this book"></MAP><TABLEWIDTH="515"BORDER="0"CELLSPACING="0"CELLPADDING="0"><TR><TDALIGN="LEFT"VALIGN="TOP"WIDTH="172"><ACLASS="SECT1"HREF="ch35_06.htm"TITLE="35.6 Low-Level File Butchery with dd "><IMGSRC="gifs/txtpreva.gif"SRC="gifs/txtpreva.gif"ALT="Previous: 35.6 Low-Level File Butchery with dd "BORDER="0"></A></TD><TDALIGN="CENTER"VALIGN="TOP"WIDTH="171"><B><FONTFACE="ARIEL,HELVETICA,HELV,SANSERIF"SIZE="-1">Chapter 35<BR>You Can't Quite Call This Editing</FONT></B></TD><TDALIGN="RIGHT"VALIGN="TOP"WIDTH="172"><ACLASS="SECT1"HREF="ch35_08.htm"TITLE="35.8 Centering Lines in a File "><IMGSRC="gifs/txtnexta.gif"SRC="gifs/txtnexta.gif"ALT="Next: 35.8 Centering Lines in a File "BORDER="0"></A></TD></TR></TABLE> <HRALIGN="LEFT"WIDTH="515"TITLE="footer"></DIV><DIVCLASS="SECT1"><H2CLASS="sect1"><ACLASS="title"NAME="UPT-ART-4490">35.7 offset: Indent Text </A></H2><PCLASS="para"><ACLASS="indexterm"NAME="AUTOID-40372"></A><ACLASS="indexterm"NAME="AUTOID-40375"></A>Do you have a printer that starts each line too close to the left margin?You might want to indent text to make it look better on the screen or aprinted page.Here's a shell script that does that.It reads from files or standard input and writes to standard output.The default indentation is 5 spaces.For example, to send a copy of a file named <EMCLASS="emphasis">graph</EM> to the <EMCLASS="emphasis">lp</EM>printer, indented 12 spaces:</P><PCLASS="para"><BLOCKQUOTECLASS="screen"><PRECLASS="screen">% <CODECLASS="userinput"><B>offset -12 graph | lp</B></CODE></PRE></BLOCKQUOTE></P><PCLASS="para">There are easier ways to do this (with<SPANCLASS="link"><EMCLASS="emphasis">awk</EM> (<ACLASS="linkend"HREF="ch33_11.htm"TITLE="Quick Reference: awk ">33.11</A>)</SPAN>,for instance).This script uses the Bourne shell <EMCLASS="emphasis">case</EM> statement in an interesting waythough, and that might give you ideas for other work.</P><PCLASS="para"><BLOCKQUOTECLASS="screen"><PRECLASS="screen"> #! /bin/sh# GET INDENTATION (IF ANY) AND CHECK FOR BOGUS NUMBERS:case "$1" in-[0-9]|-[0-9][0-9]) indent="$1"; shift ;;-*) echo "`basename $0`: '$1' isn't -number or is > 99." 1>&2; exit 1 ;;esac# SET DEFAULT:case "$indent" in"") indent=-5 ;;esac# BUILD THE SPACES FOR sed.# FIRST case DOES MULTIPLES OF 10; SECOND case DOES SINGLE SPACES:s=" " # TEN SPACEScase "$indent" in-?) ;; # LESS THAN 10; SKIP IT-1?) pad="$s" ;;-2?) pad="$s$s" ;;-3?) pad="$s$s$s" ;;-4?) pad="$s$s$s$s" ;;-5?) pad="$s$s$s$s$s" ;;-6?) pad="$s$s$s$s$s$s" ;;-7?) pad="$s$s$s$s$s$s$s" ;;-8?) pad="$s$s$s$s$s$s$s$s" ;;-9?) pad="$s$s$s$s$s$s$s$s$s" ;;*) echo "`basename $0`: Help! \$indent is '$indent'!?!" 1>&2; exit 1 ;;esaccase "$indent" in-0|-?0) ;; # SKIP IT; IT'S A MULTIPLE OF 10-1|-?1) pad="$pad " ;;-2|-?2) pad="$pad " ;;-3|-?3) pad="$pad " ;;-4|-?4) pad="$pad " ;;-5|-?5) pad="$pad " ;;-6|-?6) pad="$pad " ;;-7|-?7) pad="$pad " ;;-8|-?8) pad="$pad " ;;-9|-?9) pad="$pad " ;;*) echo "`basename $0`: Help! \$indent is '$indent'!?!" 1>&2; exit 1 ;;esac# MIGHT ADD expand FIRST TO TAKE CARE OF TABS:sed "s/^/$pad/" $*</PRE></BLOCKQUOTE></P><PCLASS="para">First, the script sets the indentation amount, like <CODECLASS="literal">-12</CODE> or<CODECLASS="literal">-5</CODE>, in the <EMCLASS="emphasis">indent</EM> variable.Next, it builds a shell variable, <EMCLASS="emphasis">pad</EM>, with just enough spaces toindent the text.One <EMCLASS="emphasis">case</EM> checks the first digit of <CODECLASS="literal">$indent</CODE> to find out howmany ten-space chunks of spaces to put in <EMCLASS="emphasis">pad</EM>.The next <EMCLASS="emphasis">case</EM> finishes the job with a few more spaces.A<SPANCLASS="link"><EMCLASS="emphasis">sed</EM> (<ACLASS="linkend"HREF="ch34_24.htm"TITLE="Quick Reference: sed ">34.24</A>)</SPAN>command adds the spaces to the start of each line.If your lines have TABs in them, change the last line to use<SPANCLASS="link"><EMCLASS="emphasis">expand</EM> or <EMCLASS="emphasis">pr -e -t</EM> (<ACLASS="linkend"HREF="ch41_04.htm"TITLE="How UNIX Handles TAB Characters ">41.4</A>)</SPAN>and pipe the result to <EMCLASS="emphasis">sed</EM>:</P><PCLASS="para"><BLOCKQUOTECLASS="screen"><PRECLASS="screen">expand $* | sed "s/^/$pad/"</PRE></BLOCKQUOTE></P><ACLASS="indexterm"NAME="AUTOID-40406"></A><DIVCLASS="sect1info"><PCLASS="SECT1INFO">- <SPANCLASS="authorinitials">JP</SPAN></P></DIV></DIV><DIVCLASS="htmlnav"><P></P><HRALIGN="LEFT"WIDTH="515"TITLE="footer"><TABLEWIDTH="515"BORDER="0"CELLSPACING="0"CELLPADDING="0"><TR><TDALIGN="LEFT"VALIGN="TOP"WIDTH="172"><ACLASS="SECT1"HREF="ch35_06.htm"TITLE="35.6 Low-Level File Butchery with dd "><IMGSRC="gifs/txtpreva.gif"SRC="gifs/txtpreva.gif"ALT="Previous: 35.6 Low-Level File Butchery with dd "BORDER="0"></A></TD><TDALIGN="CENTER"VALIGN="TOP"WIDTH="171"><ACLASS="book"HREF="index.htm"TITLE="UNIX Power Tools"><IMGSRC="gifs/txthome.gif"SRC="gifs/txthome.gif"ALT="UNIX Power Tools"BORDER="0"></A></TD><TDALIGN="RIGHT"VALIGN="TOP"WIDTH="172"><ACLASS="SECT1"HREF="ch35_08.htm"TITLE="35.8 Centering Lines in a File "><IMGSRC="gifs/txtnexta.gif"SRC="gifs/txtnexta.gif"ALT="Next: 35.8 Centering Lines in a File "BORDER="0"></A></TD></TR><TR><TDALIGN="LEFT"VALIGN="TOP"WIDTH="172">35.6 Low-Level File Butchery with dd </TD><TDALIGN="CENTER"VALIGN="TOP"WIDTH="171"><ACLASS="index"HREF="index/idx_0.htm"TITLE="Book Index"><IMGSRC="gifs/index.gif"SRC="gifs/index.gif"ALT="Book Index"BORDER="0"></A></TD><TDALIGN="RIGHT"VALIGN="TOP"WIDTH="172">35.8 Centering Lines in a File </TD></TR></TABLE><HRALIGN="LEFT"WIDTH="515"TITLE="footer"><IMGSRC="gifs/smnavbar.gif"SRC="gifs/smnavbar.gif"USEMAP="#map"BORDER="0"ALT="The UNIX CD Bookshelf Navigation"><MAPNAME="map"><AREASHAPE="RECT"COORDS="0,0,73,21"HREF="../index.htm"ALT="The UNIX CD Bookshelf"><AREASHAPE="RECT"COORDS="74,0,163,21"HREF="index.htm"ALT="UNIX Power Tools"><AREASHAPE="RECT"COORDS="164,0,257,21"HREF="../unixnut/index.htm"ALT="UNIX in a Nutshell"><AREASHAPE="RECT"COORDS="258,0,321,21"HREF="../vi/index.htm"ALT="Learning the vi Editor"><AREASHAPE="RECT"COORDS="322,0,378,21"HREF="../sedawk/index.htm"ALT="sed & awk"><AREASHAPE="RECT"COORDS="379,0,438,21"HREF="../ksh/index.htm"ALT="Learning the Korn Shell"><AREASHAPE="RECT"COORDS="439,0,514,21"HREF="../lrnunix/index.htm"ALT="Learning the UNIX Operating System"></MAP></DIV></BODY></HTML>⌨️ 快捷键说明
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