ch52_04.htm

the unix power tools

CLASS="indexterm"
NAME="AUTOID-60881"
></A
>
The <EM
CLASS="emphasis"
>catsaway</EM
> shell script is included here as an example of
using a loop to repeat a command until it fails.
Article
<A
CLASS="xref"
HREF="ch44_10.htm"
TITLE="Loops That Test Exit Status "
>44.10</A
>.</P
></DD
><DT
CLASS="term"
>center *</DT
><DD
CLASS="listitem"
><P
CLASS="para"
><A
CLASS="indexterm"
NAME="AUTOID-60889"
></A
>
<EM
CLASS="emphasis"
>center</EM
> is an <EM
CLASS="emphasis"
>awk</EM
> script that centers each line of a file.
Article
<A
CLASS="xref"
HREF="ch35_08.htm"
TITLE="Centering Lines in a File "
>35.8</A
>.</P
></DD
><DT
CLASS="term"
>cgrep *</DT
><DD
CLASS="listitem"
><P
CLASS="para"
><A
CLASS="indexterm"
NAME="AUTOID-60898"
></A
>
<EM
CLASS="emphasis"
>cgrep</EM
> is a context-<EM
CLASS="emphasis"
>grep</EM
> Perl script for showing the given
string with several lines of surrounding text.
Article
<A
CLASS="xref"
HREF="ch27_13.htm"
TITLE="More grep-like Programs Written in Perl "
>27.13</A
>.</P
></DD
><DT
CLASS="term"
>cgrep.sed *</DT
><DD
CLASS="listitem"
><P
CLASS="para"
><A
CLASS="indexterm"
NAME="AUTOID-60907"
></A
>
<EM
CLASS="emphasis"
>cgrep.sed</EM
> is a context-<EM
CLASS="emphasis"
>grep</EM
> <EM
CLASS="emphasis"
>sed</EM
> script for showing the given
string with several lines of surrounding text.
It can also match a pattern that's spread across several lines.
Articles
<A
CLASS="xref"
HREF="ch27_11.htm"
TITLE="A Multiline Context grep Using sed "
>27.11</A
>,
<A
CLASS="xref"
HREF="ch34_17.htm"
TITLE="Searching for Patterns Split Across Lines "
>34.17</A
>.</P
></DD
><DT
CLASS="term"
>checksed *</DT
><DD
CLASS="listitem"
><P
CLASS="para"
><A
CLASS="indexterm"
NAME="AUTOID-60918"
></A
>
The <EM
CLASS="emphasis"
>checksed</EM
> shell script runs the <EM
CLASS="emphasis"
>sed</EM
> commands in a
file called <EM
CLASS="emphasis"
>sedscr</EM
> on the specified files, showing the edits with
<EM
CLASS="emphasis"
>diff</EM
> and a pager program.
Article
<A
CLASS="xref"
HREF="ch34_03.htm"
TITLE="Testing and Using a sed Script: checksed, runsed "
>34.3</A
>.</P
></DD
><DT
CLASS="term"
>chmod_edit *</DT
><DD
CLASS="listitem"
><P
CLASS="para"
><A
CLASS="indexterm"
NAME="AUTOID-60929"
></A
>
The <EM
CLASS="emphasis"
>chmod_edit</EM
> shell script
adds write permission to a file, places you in your
favorite editor, and then removes write permission again.
Article
<A
CLASS="xref"
HREF="ch22_09.htm"
TITLE="Protect Important Files: Make Them Unwritable "
>22.9</A
>.</P
></DD
><DT
CLASS="term"
>chunksort *</DT
><DD
CLASS="listitem"
><P
CLASS="para"
><A
CLASS="indexterm"
NAME="AUTOID-60937"
></A
>
The <EM
CLASS="emphasis"
>chunksort</EM
> script sorts multiline records that are
separated by blank lines.
Article
<A
CLASS="xref"
HREF="ch36_07.htm"
TITLE="Sorting Multiline Entries "
>36.7</A
>.</P
></DD
><DT
CLASS="term"
>cleanup *</DT
><DD
CLASS="listitem"
><P
CLASS="para"
><A
CLASS="indexterm"
NAME="AUTOID-60945"
></A
>
<EM
CLASS="emphasis"
>cleanup</EM
> is an example of a shell script to be run by <EM
CLASS="emphasis"
>cron</EM
>.
By combining multiple <EM
CLASS="emphasis"
>find</EM
> conditions, the <EM
CLASS="emphasis"
>find</EM
> command
is run only once instead of multiple times.  
Article
<A
CLASS="xref"
HREF="ch23_22.htm"
TITLE="Using find to Clear Out Unneeded Files "
>23.22</A
>.</P
></DD
><DT
CLASS="term"
>cleanup.sed *</DT
><DD
CLASS="listitem"
><P
CLASS="para"
><A
CLASS="indexterm"
NAME="AUTOID-60956"
></A
>
<EM
CLASS="emphasis"
>cleanup.sed</EM
> is a <EM
CLASS="emphasis"
>sed</EM
> script to be run on <EM
CLASS="emphasis"
>troff</EM
> input
files.
It converts double quotes to &quot;curly&quot; quotes, two dashes to
em-dashes, and places a no-space character before constant-width font
changes.
It should be called with <EM
CLASS="emphasis"
>sed -f cleanup.sed</EM
>.
Article
<A
CLASS="xref"
HREF="ch43_21.htm"
TITLE="Preprocessing troff Input with sed "
>43.21</A
>.</P
></DD
><DT
CLASS="term"
>Clear *</DT
><DD
CLASS="listitem"
><P
CLASS="para"
><A
CLASS="indexterm"
NAME="AUTOID-60967"
></A
><A
CLASS="indexterm"
NAME="AUTOID-60969"
></A
><A
CLASS="indexterm"
NAME="AUTOID-60971"
></A
><A
CLASS="indexterm"
NAME="AUTOID-60973"
></A
><A
CLASS="indexterm"
NAME="AUTOID-60975"
></A
><A
CLASS="indexterm"
NAME="AUTOID-60977"
></A
><A
CLASS="indexterm"
NAME="AUTOID-60979"
></A
><A
CLASS="indexterm"
NAME="AUTOID-60981"
></A
>
The <EM
CLASS="emphasis"
>Clear</EM
> shell script can be used to execute VT100 escape
sequences.
It is also linked to the names <EM
CLASS="emphasis"
>NOG</EM
> (to cancel
an alternate character set); <EM
CLASS="emphasis"
>Graphics</EM
> (to enable graphics mode);
<EM
CLASS="emphasis"
>C132</EM
> (to enable 132-column mode); <EM
CLASS="emphasis"
>C80</EM
> (to enable 80-column
mode); <EM
CLASS="emphasis"
>Revvid</EM
> (to enable reverse video); <EM
CLASS="emphasis"
>Normal</EM
> (to
re-enable normal video); <EM
CLASS="emphasis"
>ToStatus</EM
> (to write a message to the
terminal status line); and <EM
CLASS="emphasis"
>ClrStatus</EM
> (to clear the status line).
Article
<A
CLASS="xref"
HREF="ch41_09.htm"
TITLE="Commands to Adjust Your Terminal "
>41.9</A
>.</P
></DD
><DT
CLASS="term"
>cls *</DT
><DD
CLASS="listitem"
><P
CLASS="para"
><A
CLASS="indexterm"
NAME="AUTOID-60997"
></A
><A
CLASS="indexterm"
NAME="AUTOID-60999"
></A
><A
CLASS="indexterm"
NAME="AUTOID-61001"
></A
><A
CLASS="indexterm"
NAME="AUTOID-61003"
></A
>
<EM
CLASS="emphasis"
>cls</EM
> is a compressed directory lister 
that can list directories in nice columns and 
indicate &quot;long&quot; names that have been truncated.
It is also linked to the names <EM
CLASS="emphasis"
>clf</EM
>, <EM
CLASS="emphasis"
>cls2</EM
>, and <EM
CLASS="emphasis"
>clf2</EM
>.
Article
<A
CLASS="xref"
HREF="ch16_06.htm"
TITLE='clf, cls: "Compressed&quot; ls Listings'
>16.6</A
>.</P
></DD
><DT
CLASS="term"
>cols *</DT
><DD
CLASS="listitem"
><P
CLASS="para"
><A
CLASS="indexterm"
NAME="AUTOID-61014"
></A
>
The <EM
CLASS="emphasis"
>cols</EM
> shell script displays output in columns.  
It is also linked to the <EM
CLASS="emphasis"
>c2</EM
>, <EM
CLASS="emphasis"
>c3</EM
>, <EM
CLASS="emphasis"
>c4</EM
>, <EM
CLASS="emphasis"
>c5</EM
>,
<EM
CLASS="emphasis"
>c6</EM
>, <EM
CLASS="emphasis"
>c7</EM
>, and <EM
CLASS="emphasis"
>c8</EM
> commands, to force it to display the
respective number of columns.
Article
<A
CLASS="xref"
HREF="ch35_16.htm"
TITLE="Make Columns Automatically with cols "
>35.16</A
>.</P
></DD
><DT
CLASS="term"
>count.it *</DT
><DD
CLASS="listitem"
><P
CLASS="para"
><A
CLASS="indexterm"
NAME="AUTOID-61029"
></A
>
<EM
CLASS="emphasis"
>count.it</EM
> reports the difference in word length between two
files.
Article
<A
CLASS="xref"
HREF="ch29_06.htm"
TITLE="Counting Lines, Words, and Characters: wc "
>29.6</A
>.</P
></DD
><DT
CLASS="term"
>count_types *</DT
><DD
CLASS="listitem"
><P
CLASS="para"
><A
CLASS="indexterm"
NAME="AUTOID-61037"
></A
>
<EM
CLASS="emphasis"
>count_types</EM
> is a shell script that reports the number of
files of each type, as reported by the <EM
CLASS="emphasis"
>file</EM
> command.
Article
<A
CLASS="xref"
HREF="ch16_24.htm"
TITLE="Counting Files by Types "
>16.24</A
>.</P
></DD
><DT
CLASS="term"
>cpmod</DT
><DD
CLASS="listitem"
><P
CLASS="para"
><A
CLASS="indexterm"
NAME="AUTOID-61046"
></A
>
<EM
CLASS="emphasis"
>cpmod</EM
> allows you to copy modes, ownerships, and times 
from one file to others, without affecting the data.
Article
<A
CLASS="xref"
HREF="ch22_16.htm"
TITLE="Copying Permissions with cpmod "
>22.16</A
>.</P
></DD
><DT
CLASS="term"
>crontab *</DT
><DD
CLASS="listitem"
><P
CLASS="para"
><A
CLASS="indexterm"
NAME="AUTOID-61054"
></A
>
The <EM
CLASS="emphasis"
>crontab</EM
> shell script provides interactive editing of your
<EM
CLASS="emphasis"
>crontab</EM
> entries.
This script is meant for systems that
do not already provide interactive <EM
CLASS="emphasis"
>crontab</EM
> file editing.
Article
<A
CLASS="xref"
HREF="ch40_15.htm"
TITLE="crontab Script Makes crontab Editing Easier/Safer "
>40.15</A
>.</P
></DD
><DT
CLASS="term"
>crush *</DT
><DD
CLASS="listitem"
><P
CLASS="para"
><A
CLASS="indexterm"
NAME="AUTOID-61064"
></A
>
<EM
CLASS="emphasis"
>crush</EM
> is a <EM
CLASS="emphasis"
>sed</EM
> script that removes blank lines
from text and sends the result to standard output.
Article
<A
CLASS="xref"
HREF="ch25_11.htm"
TITLE="crush: A cat that Skips all Blank Lines "
>25.11</A
>.</P
></DD
><DT
CLASS="term"
>csh_init *</DT
><DD
CLASS="listitem"
><P
CLASS="para"
><A
CLASS="indexterm"
NAME="AUTOID-61073"
></A
>
The <EM
CLASS="emphasis"
>csh_init</EM
> file is a collection of C shell commands and alias
definitions that are shown throughout the book.
Most of these are also available as Bourne-type shell functions 
in the <EM
CLASS="emphasis"
>sh_init</EM
> file.</P
><P
CLASS="para"
>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 or 
<SPAN
CLASS="link"
>source (<A
CLASS="linkend"
HREF="ch44_23.htm"
TITLE="Reading Files with the . and source Commands "
>44.23</A
>)</SPAN
>
the file into your
<SPAN
CLASS="link"
>shell setup file (<A
CLASS="linkend"
HREF="ch02_02.htm"
TITLE="Shell Setup Files-Which, Where, and Why "
>2.2</A
>)</SPAN
>,
and then enable the 
definitions that you want.
Articles
<A
CLASS="xref"
HREF="ch02_15.htm"
TITLE="Unclutter Logins: Show Login Messages Just Once "
>2.15</A
>,
<A
CLASS="xref"
HREF="ch07_05.htm"
TITLE="Multiline Shell Prompts "
>7.5</A
>,
<A
CLASS="xref"
HREF="ch07_06.htm"
TITLE="Session Information in Your Terminal's Status Line "
>7.6</A
>,
<A
CLASS="xref"
HREF="ch07_08.htm"
TITLE="Highlighting in Shell Prompts "
>7.8</A
>,
<A
CLASS="xref"
HREF="ch07_11.htm"
TITLE="dirs in Your Prompt: Better than $cwd "
>7.11</A
>,
<A
CLASS="xref"
HREF="ch10_07.htm"
TITLE="How to Put if-then-else in a C Shell Alias "
>10.7</A
>,
<A
CLASS="xref"
HREF="ch10_08.htm"
TITLE="Fix Quoting in csh Aliases with makealias and quote "
>10.8</A
>,
<A
CLASS="xref"
HREF="ch14_09.htm"
TITLE="cd by Directory Initials "
>14.9</A
>,
<A
CLASS="xref"
HREF="ch14_14.htm"
TITLE="Automatic Setup When You Enter/Exit a Directory "
>14.14</A
>,
<A
CLASS="xref"
HREF="ch15_05.htm"
TITLE='Matching All "Dot Files&quot; with Wildcards'
>15.5</A
>,
<A
CLASS="xref"
HREF="ch16_26.htm"
TITLE="Finding Text Files with findtext "
>16.26</A
>,
<A
CLASS="xref"
HREF="ch17_23.htm"
TITLE="Finding Files with -prune "
>17.23</A
>,
<A
CLASS="xref"
HREF="ch21_14.htm"
TITLE="Automatically Appending the Date to a Filename "
>21.14</A
>,
<A
CLASS="xref"
HREF="ch22_02.htm"
TITLE="Tutorial on File and Directory Permissions "
>22.2</A
>,
<A
CLASS="xref"
HREF="ch22_09.htm"
TITLE="Protect Important Files: Make Them Unwritable "
>22.9</A
>,
<A
CLASS="xref"
HREF="ch25_17.htm"
TITLE="An Alias in Case You Don't Have tail "
>25.17</A
>,
<A
CLASS="xref"
HREF="ch29_08.htm"
TITLE="Find a a Doubled Word "
>29.8</A
>,
<A
CLASS="xref"
HREF="ch30_20.htm"
TITLE="Multiple Editor Setup Files; Starting with a Search "
>30.20</A
>,
<A
CLASS="xref"
HREF="ch43_08.htm"
TITLE="Fixing Margins with pr and fold "
>43.8</A
>,
<A
CLASS="xref"
HREF="ch47_05.htm"
TITLE="Using C Shell Arrays "
>47.5</A
>,
and
<A
CLASS="xref"
HREF="ch50_08.htm"
TITLE="Which Version Am I Using? "
>50.8</A
>.</P
></DD
><DT
CLASS="term"
>csh_logout *</DT
><DD
CLASS="listitem"
><P
CLASS="para"
><A
CLASS="indexterm"
NAME="AUTOID-61105"
></A
>
The <EM
CLASS="emphasis"
>csh_logout</EM
> file contains a set of commands for
removing temporary files.
C shell users can input these commands 
into their <EM
CLASS="emphasis"
>~/.logout</EM
> file.
Article
<A
CLASS="xref"
HREF="ch21_03.htm"
TITLE="Unique Names for Temporary Files "
>21.3</A
>.</P
></DD
><DT
CLASS="term"
>csplit</DT
><DD
CLASS="listitem"
><P
CLASS="para"
><A
CLASS="indexterm"
NAME="AUTOID-61114"
></A
>
The <EM
CLASS="emphasis"
>csplit</EM
> program splits a file according to context.
<EM
CLASS="emphasis"
>csplit</EM
> is part of the <EM
CLASS="emphasis"
>textutils</EM
> package.
Article
<A
CLASS="xref"
HREF="ch35_10.htm"
TITLE="Splitting Files by Context: csplit "
>35.10</A
>.</P
></DD
><DT
CLASS="term"
>cut+paste</DT
><DD
CLASS="listitem"
><P
CLASS="para"
><A
CLASS="indexterm"
NAME="AUTOID-61124"
></A
><A
CLASS="indexterm"
NAME="AUTOID-61126"
></A
><A
CLASS="indexterm"
NAME="AUTOID-61128"
></A
>
<EM
CLASS="emphasis"
>cut</EM
> and <EM
CLASS="emphasis"
>paste</EM
> are public domain versions of AT&amp;T's <EM
CLASS="emphasis"
>cut</EM
> and
<EM
CLASS="emphasis"
>paste</EM
> commands. They are part of the GNU <EM
CLASS="emphasis"
>textutils</EM
>
package. Articles
<A