ch52_04.htm

the unix power tools

CLASS="xref"
HREF="ch35_14.htm"
TITLE="Cutting Columns or Fields with cut "
>35.14</A
>
and
<A
CLASS="xref"
HREF="ch35_18.htm"
TITLE="Pasting Things in Columns "
>35.18</A
>.</P
></DD
><DT
CLASS="term"
>cvtbase</DT
><DD
CLASS="listitem"
><P
CLASS="para"
><A
CLASS="indexterm"
NAME="AUTOID-61141"
></A
>
<EM
CLASS="emphasis"
>cvtbase</EM
> is a program for converting from one base to another.
Supported bases are decimal, hexadecimal, octal, and binary.
Article
<A
CLASS="xref"
HREF="ch49_05.htm"
TITLE="Base Conversion Using cvtbase "
>49.5</A
>.</P
></DD
><DT
CLASS="term"
>del *</DT
><DD
CLASS="listitem"
><P
CLASS="para"
><A
CLASS="indexterm"
NAME="AUTOID-61149"
></A
>
<EM
CLASS="emphasis"
>del</EM
> is a shell script that prompts you for the removal 
of the specified files.
Unlike <EM
CLASS="emphasis"
>rm -i</EM
>, <EM
CLASS="emphasis"
>del</EM
> prompts
you only once for all files when there are more than three to remove.
Article
<A
CLASS="xref"
HREF="ch23_06.htm"
TITLE="A Faster Way to Remove Files Interactively "
>23.6</A
>.</P
></DD
><DT
CLASS="term"
>delete</DT
><DD
CLASS="listitem"
><P
CLASS="para"
><A
CLASS="indexterm"
NAME="AUTOID-61159"
></A
><A
CLASS="indexterm"
NAME="AUTOID-61161"
></A
><A
CLASS="indexterm"
NAME="AUTOID-61163"
></A
><A
CLASS="indexterm"
NAME="AUTOID-61165"
></A
><A
CLASS="indexterm"
NAME="AUTOID-61167"
></A
>
The <EM
CLASS="emphasis"
>delete</EM
> program is a replacement for <EM
CLASS="emphasis"
>rm</EM
> that 
allows files to be recovered later on.
Instead of actually
deleting files, <EM
CLASS="emphasis"
>delete</EM
> marks them for deletion by adding
a <CODE
CLASS="literal"
>.#</CODE
> prefix.
To recover the file, use <EM
CLASS="emphasis"
>undelete</EM
>.
To delete the files for real, use <EM
CLASS="emphasis"
>expunge</EM
>
or <EM
CLASS="emphasis"
>purge</EM
>.
To list all the files in the
current directory that are marked for deletion, use the
<EM
CLASS="emphasis"
>lsdel</EM
> command.
Article 
<A
CLASS="xref"
HREF="ch23_09.htm"
TITLE="delete: Protecting Files from Accidental Deletion "
>23.9</A
>.</P
></DD
><DT
CLASS="term"
>GNU diff, diff3, sdiff, and cmp Utilities</DT
><DD
CLASS="listitem"
><P
CLASS="para"
><A
CLASS="indexterm"
NAME="AUTOID-61182"
></A
><A
CLASS="indexterm"
NAME="AUTOID-61184"
></A
><A
CLASS="indexterm"
NAME="AUTOID-61186"
></A
><A
CLASS="indexterm"
NAME="AUTOID-61188"
></A
>
The GNU versions of <EM
CLASS="emphasis"
>diff</EM
>, <EM
CLASS="emphasis"
>diff3</EM
>, <EM
CLASS="emphasis"
>sdiff</EM
>, 
and <EM
CLASS="emphasis"
>cmp</EM
> provide all the 
features of BSD's versions, but with some additional features.
Articles
<A
CLASS="xref"
HREF="ch28_01.htm#UPT-ART-2680"
TITLE="Checking Differences with diff "
>28.1</A
>,
<A
CLASS="xref"
HREF="ch28_02.htm"
TITLE="Comparing Three Different Versions with diff3 "
>28.2</A
>,
<A
CLASS="xref"
HREF="ch28_04.htm"
TITLE="Side-by-Side diffs: sdiff "
>28.4</A
>,
and
<A
CLASS="xref"
HREF="ch28_11.htm"
TITLE="cmp and diff "
>28.11</A
>.</P
></DD
><DT
CLASS="term"
>dir_path *</DT
><DD
CLASS="listitem"
><P
CLASS="para"
><A
CLASS="indexterm"
NAME="AUTOID-61202"
></A
>
<EM
CLASS="emphasis"
>dir_path</EM
> is a shell script that shows all directories 
with the same name.
Article
<A
CLASS="xref"
HREF="ch16_21.htm"
TITLE="Finding All Directories with the Same Name "
>16.21</A
>.</P
></DD
><DT
CLASS="term"
>dirtop *</DT
><DD
CLASS="listitem"
><P
CLASS="para"
><A
CLASS="indexterm"
NAME="AUTOID-61210"
></A
>
The <EM
CLASS="emphasis"
>dirtop</EM
> shell script uses VT100 escape sequences to 
make an <EM
CLASS="emphasis"
>ls</EM
> directory listing that stays at the top of the window
while you work.
Article
<A
CLASS="xref"
HREF="ch21_10.htm"
TITLE="Keep a Directory Listing at Top of the Screen: dirtop "
>21.10</A
>.</P
></DD
><DT
CLASS="term"
>doublespace *</DT
><DD
CLASS="listitem"
><P
CLASS="para"
><A
CLASS="indexterm"
NAME="AUTOID-61219"
></A
>
<EM
CLASS="emphasis"
>doublespace</EM
> is a <EM
CLASS="emphasis"
>sed</EM
> script that double-spaces text and
sends the result to standard output.
Article
<A
CLASS="xref"
HREF="ch25_12.htm"
TITLE="Double Space, Triple Space ... "
>25.12</A
>.</P
></DD
><DT
CLASS="term"
>ediff</DT
><DD
CLASS="listitem"
><P
CLASS="para"
><A
CLASS="indexterm"
NAME="AUTOID-61228"
></A
>
<EM
CLASS="emphasis"
>ediff</EM
> is a program that translates
<SPAN
CLASS="link"
><EM
CLASS="emphasis"
>diff</EM
> (<A
CLASS="linkend"
HREF="ch28_01.htm#UPT-ART-2680"
TITLE="Checking Differences with diff "
>28.1</A
>)</SPAN
>
output into 
English.
Article
<A
CLASS="xref"
HREF="ch28_08.htm"
TITLE="More Friendly diff Output "
>28.8</A
>.</P
></DD
><DT
CLASS="term"
>elookfor *</DT
><DD
CLASS="listitem"
><P
CLASS="para"
><A
CLASS="indexterm"
NAME="AUTOID-61238"
></A
>
The <EM
CLASS="emphasis"
>elookfor</EM
> script is similar to the <EM
CLASS="emphasis"
>lookfor</EM
> script,
but faster.
It finds all files in the given directory tree
that contain the given string(s), using <EM
CLASS="emphasis"
>egrep</EM
>.  
Article 
<A
CLASS="xref"
HREF="ch17_21.htm"
TITLE="lookfor: Which File Has that Word? "
>17.21</A
>.</P
></DD
><DT
CLASS="term"
>GNU emacs, Version 19.3.1</DT
><DD
CLASS="listitem"
><P
CLASS="para"
><A
CLASS="indexterm"
NAME="AUTOID-61248"
></A
>
GNU <EM
CLASS="emphasis"
>emacs</EM
> is the GNU incarnation of the
advanced,
self-documenting, customizable, extensible real-time display editor
Emacs.  
<A
CLASS="xref"
HREF="ch32_01.htm"
TITLE="GNU Emacs"
>Chapter 32, GNU Emacs</A
>.</P
></DD
><DT
CLASS="term"
>GNU expand</DT
><DD
CLASS="listitem"
><P
CLASS="para"
><A
CLASS="indexterm"
NAME="AUTOID-61256"
></A
>
GNU <EM
CLASS="emphasis"
>expand</EM
> converts TAB characters into the
corresponding number of spaces.
<EM
CLASS="emphasis"
>expand</EM
> is part of the <EM
CLASS="emphasis"
>textutils</EM
> package.
Article
<A
CLASS="xref"
HREF="ch41_04.htm"
TITLE="How UNIX Handles TAB Characters "
>41.4</A
>.</P
></DD
><DT
CLASS="term"
>Expect, Version 5.22</DT
><DD
CLASS="listitem"
><P
CLASS="para"
><A
CLASS="indexterm"
NAME="AUTOID-61266"
></A
>
Expect is a program to control interactive applications, such as
<EM
CLASS="emphasis"
>telnet</EM
> and <EM
CLASS="emphasis"
>passwd</EM
>,
that prompt you to type something at the prompt.
You can write simple Expect scripts to automate these interactions.
Then the Expect script can run the &quot;interactive&quot; program
non-interactively.
Expect is part of the <EM
CLASS="emphasis"
>Tcl/tk</EM
> package.
Article
<A
CLASS="xref"
HREF="ch09_26.htm"
TITLE="Expect "
>9.26</A
>.</P
></DD
><DT
CLASS="term"
>exrc *</DT
><DD
CLASS="listitem"
><P
CLASS="para"
><A
CLASS="indexterm"
NAME="AUTOID-61276"
></A
>
The <EM
CLASS="emphasis"
>exrc</EM
> file is a collection of <EM
CLASS="emphasis"
>vi</EM
> and <EM
CLASS="emphasis"
>ex</EM
> commands 
that are shown throughout the book.
In its distribution
form, each set of commands is commented out and needs to be explicitly
uncommented before you can use them; this is because many of the
definitions override or conflict with one another.
You can copy 
this file into your
<SPAN
CLASS="link"
><EM
CLASS="emphasis"
>.exrc</EM
> file (<A
CLASS="linkend"
HREF="ch04_09.htm"
TITLE="Setting Up vi with the .exrc File "
>4.9</A
>)</SPAN
>,
and then enable the 
definitions that you want.
Articles
<A
CLASS="xref"
HREF="ch30_23.htm"
TITLE="Safer vi Filter-Throughs "
>30.23</A
>,
<A
CLASS="xref"
HREF="ch30_32.htm"
TITLE="Using vi Abbreviations as Commands (Cut and Paste Between vi's)"
>30.32</A
>,
<A
CLASS="xref"
HREF="ch31_05.htm"
TITLE="Keymaps for Pasting into a Window Running vi "
>31.5</A
>,
<A
CLASS="xref"
HREF="ch31_09.htm"
TITLE="Good Stuff for Your .exrc File "
>31.9</A
>,
<A
CLASS="xref"
HREF="ch31_12.htm"
TITLE="Text-Input Mode Cursor Motion with No Arrow Keys "
>31.12</A
>,
<A
CLASS="xref"
HREF="ch31_13.htm"
TITLE="Making Cursor Keys Work in vi Text-input Mode "
>31.13</A
>,
and 
<A
CLASS="xref"
HREF="ch31_16.htm"
TITLE="vi Macro for Splitting Long Lines "
>31.16</A
>.</P
></DD
><DT
CLASS="term"
>fgrep, Version 1.1</DT
><DD
CLASS="listitem"
><P
CLASS="para"
><A
CLASS="indexterm"
NAME="AUTOID-61294"
></A
>
Although maligned for its slowness, <EM
CLASS="emphasis"
>fgrep</EM
> has several features
that make it worth installing.
This is one of the fastest <EM
CLASS="emphasis"
>fgreps</EM
> that we've been able to find.
Article
<A
CLASS="xref"
HREF="ch27_06.htm"
TITLE="Fast grep Isn't "
>27.6</A
>.</P
></DD
><DT
CLASS="term"
>GNU File Management Utilities (fileutils), Version 3.13</DT
><DD
CLASS="listitem"
><P
CLASS="para"
><A
CLASS="indexterm"
NAME="AUTOID-61303"
></A
><A
CLASS="indexterm"
NAME="AUTOID-61305"
></A
>
The GNU file utilities have significant advantages over their 
standard UNIX
counterparts, such as greater speed, additional options, and fewer
arbitrary limits.
Programs included are:
<EM
CLASS="emphasis"
>chmod</EM
>,<A
CLASS="indexterm"
NAME="AUTOID-61308"
></A
>
<EM
CLASS="emphasis"
>chgrp</EM
>,<A
CLASS="indexterm"
NAME="AUTOID-61311"
></A
>
<EM
CLASS="emphasis"
>chown</EM
>,<A
CLASS="indexterm"
NAME="AUTOID-61314"
></A
>
<EM
CLASS="emphasis"
>cp</EM
>,<A
CLASS="indexterm"
NAME="AUTOID-61317"
></A
>
<EM
CLASS="emphasis"
>dd</EM
>,<A
CLASS="indexterm"
NAME="AUTOID-61320"
></A
>
<EM
CLASS="emphasis"
>df</EM
>,<A
CLASS="indexterm"
NAME="AUTOID-61323"
></A
>
<EM
CLASS="emphasis"
>du</EM
>,<A
CLASS="indexterm"
NAME="AUTOID-61326"
></A
>
<EM
CLASS="emphasis"
>install</EM
>,<A
CLASS="indexterm"
NAME="AUTOID-61329"
></A
>
<EM
CLASS="emphasis"
>ln</EM
>,<A
CLASS="indexterm"
NAME="AUTOID-61332"
></A
>
<EM
CLASS="emphasis"
>ls</EM
>,<A
CLASS="indexterm"
NAME="AUTOID-61335"
></A
>
<EM
CLASS="emphasis"
>mkdir</EM
>,<A
CLASS="indexterm"
NAME="AUTOID-61338"
></A
>
<EM
CLASS="emphasis"
>mkfifo</EM
>,<A
CLASS="indexterm"
NAME="AUTOID-61341"
></A
>
<EM
CLASS="emphasis"
>mknod</EM
>,<A
CLASS="indexterm"
NAME="AUTOID-61344"
></A
>
<EM
CLASS="emphasis"
>mv</EM
>,<A
CLASS="indexterm"
NAME="AUTOID-61347"
></A
>
<EM
CLASS="emphasis"
>rm</EM
>,<A
CLASS="indexterm"
NAME="AUTOID-61350"
></A
>
<EM
CLASS="emphasis"
>rmdir</EM
>,<A
CLASS="indexterm"
NAME="AUTOID-61353"
></A
>
and
<EM
CLASS="emphasis"
>touch</EM
>.<A
CLASS="indexterm"
NAME="AUTOID-61356"
></A
>
Most of these programs are covered throughout the book.</P
></DD
><DT
CLASS="term"
>GNU find, Version 4.1</DT
><DD
CLASS="listitem"
><P
CLASS="para"
><A
CLASS="indexterm"
NAME="AUTOID-61362"
></A
><A
CLASS="indexterm"
NAME="AUTOID-61364"
></A
><A
CLASS="indexterm"
NAME="AUTOID-61366"
></A
>
GNU <EM
CLASS="emphasis"
>find</EM
> has several enhancements over the standard <EM
CLASS="emphasis"
>find</EM
>
command found on most systems.
Among other things, it has the
option to measure times 
from the beginning of today rather than from 24 hours ago, and 
it has user-settable maximum search depth.
Articles
<A
CLASS="xref"
HREF="ch17_01.htm#UPT-ART-7410"
TITLE="The find Command Is Great; The Problem Is Finding How to Use It"
>17.1</A
>
and
<A
CLASS="xref"
HREF="ch17_23.htm"
TITLE="Finding Files with -prune "
>17.23</A
>.</P
><P
CLASS="para"
><EM
CLASS="emphasis"
>find</EM
> is also distributed with the GNU <EM
CLASS="emphasis"
>xargs</EM
> program,
which is used to execute a command with many arguments.
Its <EM
CLASS="emphasis"
>-0</EM
> option works with GNU <EM
CLASS="emphasis"
>find</EM
> to avoid
problems with the standard <EM
CLASS="emphasis"
>xargs</EM
>.
Articles
<A
CLASS="xref"
HREF="ch09_21.htm"
TITLE="Handle Too-Long Command Lines with xargs "
>9.21</A
>
and
<A
CLASS="xref"
HREF="ch09_22.htm"
TITLE="xargs: Problems with Spaces and Newlines "
>9.22</A
>.</P
><P
CLASS="para"
>Finally, the package includes the GNU <EM
CLASS="emphasis"
>locate</EM
>
program, which lists files in a database that match a pattern
(similar to the
&quot;fast <EM
CLASS="emphasis"
>find</EM
>&quot;
on many systems).
Article
<A
CLASS="xref"
HREF="ch17_18.htm"
TITLE='Using "Fast find&quot;'
>17.18</A
>.</P
></DD
><DT
CLASS="term"
>findcmd *</DT
><DD
CLASS="listitem"
><P
CLASS="para"
><A
CLASS="indexterm"
NAME="AUTOID-61388"
></A
>
<EM
CLASS="emphasis"
>findcmd</EM
> searches your path and prints any program's
filename that contains the given substring.
Article
<A
CLASS="xref"
HREF="ch16_10.htm"
TITLE="findcmd: Find a Command in Your Search Path "
>16.10</A
>.</P
></DD
><DT
CLASS="term"
>findtext *</DT
><DD
CLASS="listitem"
><P
CLASS="para"