textproc.html

一本完整的描述Unix Shell 编程的工具书的所有范例

>). The GNU version
	    of <B
CLASS="COMMAND"
>tr</B
> resembles the BSD one, so quoting
	    letter ranges within brackets is mandatory.
	    </P
></DIV
></TD
></TR
></TABLE
></DD
><DT
><A
NAME="FOLDREF"
></A
><B
CLASS="COMMAND"
>fold</B
></DT
><DD
><P
>A filter that wraps lines of input to a specified width.
	      This is especially useful with the <TT
CLASS="OPTION"
>-s</TT
>
	      option, which breaks lines at word spaces (see <A
HREF="textproc.html#EX50"
>Example 12-23</A
> and <A
HREF="contributed-scripts.html#MAILFORMAT"
>Example A-1</A
>).</P
></DD
><DT
><B
CLASS="COMMAND"
>fmt</B
></DT
><DD
><P
>Simple-minded file formatter, used as a filter in a
	      pipe to <SPAN
CLASS="QUOTE"
>"wrap"</SPAN
> long lines of text
	      output.</P
><DIV
CLASS="EXAMPLE"
><HR><A
NAME="EX50"
></A
><P
><B
>Example 12-23. Formatted file listing.</B
></P
><TABLE
BORDER="0"
BGCOLOR="#E0E0E0"
WIDTH="90%"
><TR
><TD
><PRE
CLASS="PROGRAMLISTING"
>   1&nbsp;#!/bin/bash
   2&nbsp;
   3&nbsp;WIDTH=40                    # 40 columns wide.
   4&nbsp;
   5&nbsp;b=`ls /usr/local/bin`       # Get a file listing...
   6&nbsp;
   7&nbsp;echo $b | fmt -w $WIDTH
   8&nbsp;
   9&nbsp;# Could also have been done by
  10&nbsp;#    echo $b | fold - -s -w $WIDTH
  11&nbsp; 
  12&nbsp;exit 0</PRE
></TD
></TR
></TABLE
><HR></DIV
><P
>See also <A
HREF="moreadv.html#EX41"
>Example 12-5</A
>.</P
><DIV
CLASS="TIP"
><TABLE
CLASS="TIP"
WIDTH="90%"
BORDER="0"
><TR
><TD
WIDTH="25"
ALIGN="CENTER"
VALIGN="TOP"
><IMG
SRC="common/tip.png"
HSPACE="5"
ALT="Tip"></TD
><TD
ALIGN="LEFT"
VALIGN="TOP"
><P
>A powerful alternative to <B
CLASS="COMMAND"
>fmt</B
> is
	      Kamil Toman's <B
CLASS="COMMAND"
>par</B
>
	      utility, available from <A
HREF="http://www.cs.berkeley.edu/~amc/Par/"
TARGET="_top"
>http://www.cs.berkeley.edu/~amc/Par/</A
>.
	      </P
></TD
></TR
></TABLE
></DIV
></DD
><DT
><B
CLASS="COMMAND"
>col</B
></DT
><DD
><P
>This deceptively named filter removes reverse line feeds
	      from an input stream. It also attempts to replace
	      whitespace with equivalent tabs. The chief use of
	      <B
CLASS="COMMAND"
>col</B
> is in filtering the output
	      from certain text processing utilities, such as
	      <B
CLASS="COMMAND"
>groff</B
> and <B
CLASS="COMMAND"
>tbl</B
>.</P
></DD
><DT
><B
CLASS="COMMAND"
>column</B
></DT
><DD
><P
>Column formatter. This filter transforms list-type
	      text output into a <SPAN
CLASS="QUOTE"
>"pretty-printed"</SPAN
> table
	      by inserting tabs at appropriate places.</P
><DIV
CLASS="EXAMPLE"
><HR><A
NAME="COL"
></A
><P
><B
>Example 12-24. Using <B
CLASS="COMMAND"
>column</B
> to format a directory
	        listing</B
></P
><TABLE
BORDER="0"
BGCOLOR="#E0E0E0"
WIDTH="90%"
><TR
><TD
><PRE
CLASS="PROGRAMLISTING"
>   1&nbsp;#!/bin/bash
   2&nbsp;# This is a slight modification of the example file in the "column" man page.
   3&nbsp;
   4&nbsp;
   5&nbsp;(printf "PERMISSIONS LINKS OWNER GROUP SIZE MONTH DAY HH:MM PROG-NAME\n" \
   6&nbsp;; ls -l | sed 1d) | column -t
   7&nbsp;
   8&nbsp;#  The "sed 1d" in the pipe deletes the first line of output,
   9&nbsp;#+ which would be "total        N",
  10&nbsp;#+ where "N" is the total number of files found by "ls -l".
  11&nbsp;
  12&nbsp;# The -t option to "column" pretty-prints a table.
  13&nbsp;
  14&nbsp;exit 0</PRE
></TD
></TR
></TABLE
><HR></DIV
></DD
><DT
><B
CLASS="COMMAND"
>colrm</B
></DT
><DD
><P
>Column removal filter. This removes columns (characters)
	      from a file and writes the file, lacking the range of
	      specified columns, back to <TT
CLASS="FILENAME"
>stdout</TT
>.
	      <TT
CLASS="USERINPUT"
><B
>colrm 2 4 &#60;filename</B
></TT
> removes the
	      second through fourth characters from each line of the
	      text file <TT
CLASS="FILENAME"
>filename</TT
>.</P
><DIV
CLASS="CAUTION"
><TABLE
CLASS="CAUTION"
WIDTH="90%"
BORDER="0"
><TR
><TD
WIDTH="25"
ALIGN="CENTER"
VALIGN="TOP"
><IMG
SRC="common/caution.png"
HSPACE="5"
ALT="Caution"></TD
><TD
ALIGN="LEFT"
VALIGN="TOP"
><P
>If the file contains tabs or nonprintable
	      characters, this may cause unpredictable
	      behavior. In such cases, consider using
	      <A
HREF="textproc.html#EXPANDREF"
>expand</A
> and
	      <B
CLASS="COMMAND"
>unexpand</B
> in a pipe preceding
	      <B
CLASS="COMMAND"
>colrm</B
>.</P
></TD
></TR
></TABLE
></DIV
></DD
><DT
><B
CLASS="COMMAND"
>nl</B
></DT
><DD
><P
>Line numbering filter. <TT
CLASS="USERINPUT"
><B
>nl filename</B
></TT
>
	    lists <TT
CLASS="FILENAME"
>filename</TT
> to
	    <TT
CLASS="FILENAME"
>stdout</TT
>, but inserts consecutive
	    numbers at the beginning of each non-blank line. If
	    <TT
CLASS="FILENAME"
>filename</TT
> omitted, operates on
	    <TT
CLASS="FILENAME"
>stdin.</TT
></P
><P
>The output of <B
CLASS="COMMAND"
>nl</B
> is very similar to
	      <TT
CLASS="USERINPUT"
><B
>cat -n</B
></TT
>, however, by default
	      <B
CLASS="COMMAND"
>nl</B
> does not list blank lines.</P
><DIV
CLASS="EXAMPLE"
><HR><A
NAME="LNUM"
></A
><P
><B
>Example 12-25. <B
CLASS="COMMAND"
>nl</B
>: A self-numbering script.</B
></P
><TABLE
BORDER="0"
BGCOLOR="#E0E0E0"
WIDTH="90%"
><TR
><TD
><PRE
CLASS="PROGRAMLISTING"
>   1&nbsp;#!/bin/bash
   2&nbsp;# line-number.sh
   3&nbsp;
   4&nbsp;# This script echoes itself twice to stdout with its lines numbered.
   5&nbsp;
   6&nbsp;# 'nl' sees this as line 4 since it does not number blank lines.
   7&nbsp;# 'cat -n' sees the above line as number 6.
   8&nbsp;
   9&nbsp;nl `basename $0`
  10&nbsp;
  11&nbsp;echo; echo  # Now, let's try it with 'cat -n'
  12&nbsp;
  13&nbsp;cat -n `basename $0`
  14&nbsp;# The difference is that 'cat -n' numbers the blank lines.
  15&nbsp;# Note that 'nl -ba' will also do so.
  16&nbsp;
  17&nbsp;exit 0
  18&nbsp;# -----------------------------------------------------------------</PRE
></TD
></TR
></TABLE
><HR></DIV
></DD
><DT
><B
CLASS="COMMAND"
>pr</B
></DT
><DD
><P
>Print formatting filter. This will paginate files
	      (or <TT
CLASS="FILENAME"
>stdout</TT
>) into sections suitable for
	      hard copy printing or viewing on screen.	Various options
	      permit row and column manipulation, joining lines, setting
	      margins, numbering lines, adding page headers, and merging
	      files, among other things. The <B
CLASS="COMMAND"
>pr</B
>
	      command combines much of the functionality of
	      <B
CLASS="COMMAND"
>nl</B
>, <B
CLASS="COMMAND"
>paste</B
>,
	      <B
CLASS="COMMAND"
>fold</B
>, <B
CLASS="COMMAND"
>column</B
>, and
	      <B
CLASS="COMMAND"
>expand</B
>.</P
><P
><TT
CLASS="USERINPUT"
><B
>pr -o 5 --width=65 fileZZZ | more</B
></TT
>
	     gives a nice paginated listing to screen of
	     <TT
CLASS="FILENAME"
>fileZZZ</TT
> with margins set at 5 and
	     65.</P
><P
>A particularly useful option is <TT
CLASS="OPTION"
>-d</TT
>,
	      forcing double-spacing (same effect as <B
CLASS="COMMAND"
>sed
	      -G</B
>).</P
></DD
><DT
><A
NAME="GETTEXTREF"
></A
><B
CLASS="COMMAND"
>gettext</B
></DT
><DD
><P
>The GNU <B
CLASS="COMMAND"
>gettext</B
> package is a set of
	      utilities for <A
HREF="localization.html"
>localizing</A
>
	      and translating the text output of programs into foreign
	      languages. While originally intended for C programs, it
	      now supports quite a number of programming and scripting
	      languages.</P
><P
>The  <B
CLASS="COMMAND"
>gettext</B
>
	      <I
CLASS="EMPHASIS"
>program</I
> works on shell scripts. See
	      the <TT
CLASS="REPLACEABLE"
><I
>info page</I
></TT
>.</P
></DD
><DT
><A
NAME="MSGFMTREF"
></A
><B
CLASS="COMMAND"
>msgfmt</B
></DT
><DD
><P
>A program for generating binary
	      message catalogs. It is used for <A
HREF="localization.html"
>localization</A
>.</P
></DD
><DT
><B
CLASS="COMMAND"
>iconv</B
></DT
><DD
><P
>A utility for converting file(s) to a different encoding
	      (character set). Its chief use is for <A
HREF="localization.html"
>localization</A
>.</P
><P
>	    <TABLE
BORDER="0"
BGCOLOR="#E0E0E0"
WIDTH="90%"
><TR
><TD
><PRE
CLASS="PROGRAMLISTING"
>   1&nbsp;# Convert a string from UTF-8 to UTF-16 and print to the BookList
   2&nbsp;function write_utf8_string {
   3&nbsp;    STRING=$1
   4&nbsp;    BOOKLIST=$2
   5&nbsp;    echo -n "$STRING" | iconv -f UTF8 -t UTF16 | cut -b 3- | tr -d \\n &#62;&#62; "$BOOKLIST"
   6&nbsp;}
   7&nbsp;
   8&nbsp;#  From Peter Knowles' "booklistgen.sh" script
   9&nbsp;#+ for converting files to Sony Librie format.
  10&nbsp;#  (http://booklistgensh.peterknowles.com)</PRE
></TD
></TR
></TABLE
>
	    </P
></DD
><DT
><B
CLASS="COMMAND"
>recode</B
></DT
><DD
><P
>Consider this a fancier version of
	      <B
CLASS="COMMAND"
>iconv</B
>, above. This very versatile utility
	      for converting a file to a different encoding is not part
	      of the standard Linux installation.</P
></DD
><DT
><B
CLASS="COMMAND"
>TeX</B
>, <B
CLASS="COMMAND"
>gs</B
></DT
><DD
><P
><B
CLASS="COMMAND"
>TeX</B
> and <B
CLASS="COMMAND"
>Postscript</B
>
	      are text markup languages used for preparing copy for
	      printing or formatted video display.</P
><P
><B
CLASS="COMMAND"
>TeX</B
> is Donald Knuth's elaborate
		typsetting system. It is often convenient to write a
		shell script encapsulating all the options and arguments
		passed to one of these markup languages.</P
><P
><I
CLASS="EMPHASIS"
>Ghostscript</I
>
		(<B
CLASS="COMMAND"
>gs</B
>) is a GPL-ed Postscript
		interpreter.</P
></DD
><DT
><B
CLASS="COMMAND"
>enscript</B
></DT
><DD
><P
>Utility for converting plain text file to PostScript</P
><P
>For example, <B
CLASS="COMMAND"
>enscript filename.txt -p filename.ps</B
>
	      produces the PostScript output file
	      <TT
CLASS="FILENAME"
>filename.ps</TT
>.</P
></DD
><DT
><A
NAME="GROFFREF"
></A
><B
CLASS="COMMAND"
>groff</B
>, <B
CLASS="COMMAND"
>tbl</B
>, <B
CLASS="COMMAND"
>eqn</B
></DT
><DD
><P
>Yet another text markup and display formatting language
	      is <B
CLASS="COMMAND"
>groff</B
>. This is the enhanced GNU version
	      of the venerable UNIX <B
CLASS="COMMAND"
>roff/troff</B
> display
	      and typesetting package. <I
CLASS="EMPHASIS"
>Manpages</I
>
	      use <B
CLASS="COMMAND"
>groff</B
>.</P
><P
>The <B
CLASS="COMMAND"
>tbl</B
> table processing utility
	      is considered part of <B
CLASS="COMMAND"
>groff</B
>, as its
	      function is to convert table markup into
	      <B
CLASS="COMMAND"
>groff</B
> commands.</P
><P
>The <B
CLASS="COMMAND"
>eqn</B
> equation processing utility
	      is likewise part of <B
CLASS="COMMAND"
>groff</B
>, and
	      its function is to convert equation markup into
	      <B
CLASS="COMMAND"
>groff</B
> commands.</P
><DIV
CLASS="EXAMPLE"
><HR><A
NAME="MANVIEW"
></A
><P
><B
>Example 12-26. <B
CLASS="COMMAND"
>manview</B
>: Viewing formatted manpages
      </B
></P
><TABLE
BORDER="0"
BGCOLOR="#E0E0E0"
WIDTH="90%"
><TR
><TD
><PRE
CLASS="PROGRAMLISTING"
>   1&nbsp;#!/bin/bash
   2&nbsp;# manview.sh: Formats the source of a man page for viewing.
   3&nbsp;
   4&nbsp;#  This script is useful when writing man page source.
   5&nbsp;#  It lets you look at the intermediate results on the fly
   6&nbsp;#+ while working on it.
   7&nbsp;
   8&nbsp;E_WRONGARGS=65
   9&nbsp;
  10&nbsp;if [ -z "$1" ]
  11&nbsp;then
  12&nbsp;  echo "Usage: `basename $0` filename"
  13&nbsp;  exit $E_WRONGARGS
  14&nbsp;fi
  15&nbsp;
  16&nbsp;# ---------------------------
  17&nbsp;groff -Tascii -man $1 | less
  18&nbsp;# From the man page for groff.
  19&nbsp;# ---------------------------
  20&nbsp;
  21&nbsp;#  If the man page includes tables and/or equations,
  22&nbsp;#+ then the above code will barf.
  23&nbsp;#  The following line can handle such cases.
  24&nbsp;#
  25&nbsp;#   gtbl &#60; "$1" | geqn -Tlatin1 | groff -Tlatin1 -mtty-char -man
  26&nbsp;#
  27&nbsp;#   Thanks, S.C.
  28&nbsp;
  29&nbsp;exit 0</PRE
></TD
></TR
></TABLE
><HR></DIV
></DD
><DT
><B
CLASS="COMMAND"
>lex</B
>, <B
CLASS="COMMAND"
>yacc</B
></DT
><DD
><P
>The <B
CLASS="COMMAND"
>lex</B
> lexical analyzer produces
	      programs for pattern matching. This