ch44_01.htm

the unix power tools

with command substitution, article
<A
CLASS="xref"
HREF="ch09_16.htm"
TITLE="Command Substitution "
>9.16</A
>.</P
></LI
><LI
CLASS="listitem"
><P
CLASS="para"
>Find out whether a program worked or failed with its exit status,
article
<A
CLASS="xref"
HREF="ch44_07.htm"
TITLE="Exit Status of UNIX Processes "
>44.7</A
>.</P
></LI
><LI
CLASS="listitem"
><P
CLASS="para"
>Test a program's exit status and do different things if it worked or failed,
articles
<A
CLASS="xref"
HREF="ch44_08.htm"
TITLE="Test Exit Status with the if Statement "
>44.8</A
>
and
<A
CLASS="xref"
HREF="ch44_09.htm"
TITLE="Testing Your Success "
>44.9</A
>.</P
></LI
><LI
CLASS="listitem"
><P
CLASS="para"
>Loop through a set of commands and use another command to control that loop,
article
<A
CLASS="xref"
HREF="ch44_10.htm"
TITLE="Loops That Test Exit Status "
>44.10</A
>.</P
></LI
><LI
CLASS="listitem"
><P
CLASS="para"
>Set exit status of a shell (shell script), article
<A
CLASS="xref"
HREF="ch44_11.htm"
TITLE="Set Exit Status of a Shell (Script) "
>44.11</A
>.</P
></LI
><LI
CLASS="listitem"
><P
CLASS="para"
>Handle interrupts (like CTRL-c) and other signals, article
<A
CLASS="xref"
HREF="ch44_12.htm"
TITLE="Trapping Exits Caused by Interrupts "
>44.12</A
>.</P
></LI
><LI
CLASS="listitem"
><P
CLASS="para"
>Read input from the keyboard, article
<A
CLASS="xref"
HREF="ch44_13.htm"
TITLE="read: Reading from the Keyboard "
>44.13</A
>.</P
></LI
><LI
CLASS="listitem"
><P
CLASS="para"
>Handle command-line arguments (options, filenames, etc.), article
<A
CLASS="xref"
HREF="ch44_15.htm"
TITLE="Handling Command-Line Arguments in Shell Scripts "
>44.15</A
>.</P
></LI
><LI
CLASS="listitem"
><P
CLASS="para"
>Step through arguments, or any list of words, with a <EM
CLASS="emphasis"
>for</EM
> loop,
articles
<A
CLASS="xref"
HREF="ch09_12.htm"
TITLE="The Bourne Shell for Loop "
>9.12</A
>
and
<A
CLASS="xref"
HREF="ch44_16.htm"
TITLE="Handling Command-Line Arguments with a for Loop "
>44.16</A
>.</P
></LI
><LI
CLASS="listitem"
><P
CLASS="para"
>Handle arguments with the <EM
CLASS="emphasis"
>while</EM
> and <EM
CLASS="emphasis"
>shift</EM
> commands, article
<A
CLASS="xref"
HREF="ch44_17.htm"
TITLE="Handling Arguments with while and shift "
>44.17</A
>.</P
></LI
><LI
CLASS="listitem"
><P
CLASS="para"
>Handle command-line arguments in a more standard and portable way
with <EM
CLASS="emphasis"
>getopt</EM
>, article
<A
CLASS="xref"
HREF="ch44_18.htm"
TITLE="Standard Command-Line Parsing "
>44.18</A
>.</P
></LI
><LI
CLASS="listitem"
><P
CLASS="para"
>Set shell options and command-line arguments with the <EM
CLASS="emphasis"
>set</EM
> command,
article
<A
CLASS="xref"
HREF="ch44_19.htm"
TITLE="The Bourne Shell set Command "
>44.19</A
>.</P
></LI
><LI
CLASS="listitem"
><P
CLASS="para"
>Test files and strings of characters with the <EM
CLASS="emphasis"
>test</EM
> command,
article
<A
CLASS="xref"
HREF="ch44_20.htm"
TITLE="test: Testing Files and Strings "
>44.20</A
>.</P
></LI
><LI
CLASS="listitem"
><P
CLASS="para"
>Pick a name for a new command with no conflict, article
<A
CLASS="xref"
HREF="ch44_21.htm"
TITLE="Picking a Name for a New Command "
>44.21</A
>.</P
></LI
><LI
CLASS="listitem"
><P
CLASS="para"
>Find the name of a program and use it in the script, article
<A
CLASS="xref"
HREF="ch44_22.htm"
TITLE="Finding a Program Name; Multiple Program Names "
>44.22</A
>.</P
></LI
><LI
CLASS="listitem"
><P
CLASS="para"
>Use &quot;subprograms&quot; that can change the current environment, article
<A
CLASS="xref"
HREF="ch44_23.htm"
TITLE="Reading Files with the . and source Commands "
>44.23</A
>.</P
></LI
></UL
><P
CLASS="para"
>This chapter discusses only Bourne shell programming.
In most cases, the C shell
<SPAN
CLASS="link"
>isn't great for shell programming (<A
CLASS="linkend"
HREF="ch47_02.htm"
TITLE="C Shell Programming Considered Harmful "
>47.2</A
>)</SPAN
>.</P
><P
CLASS="para"
><A
CLASS="indexterm"
NAME="AUTOID-50013"
></A
>A note about command versions: 
unfortunately, the same commands on different versions of UNIX can
have different options.
Some Bourne shells are a little different from others.
For instance, some
<SPAN
CLASS="link"
><EM
CLASS="emphasis"
>test</EM
> (<A
CLASS="linkend"
HREF="ch44_20.htm"
TITLE="test: Testing Files and Strings "
>44.20</A
>)</SPAN
>
commands have a <EM
CLASS="emphasis"
>-x</EM
> option to test for an
executable file; others don't.
As article
<A
CLASS="xref"
HREF="ch46_10.htm"
TITLE="A Portable echo Command "
>46.10</A
>
explains,
some <EM
CLASS="emphasis"
>echo</EM
> commands use a <EM
CLASS="emphasis"
>-n</EM
> option to mean &quot;no newline at the
end of this string&quot;; others have you put <CODE
CLASS="literal"
>\c</CODE
> at the end of the string.
And so on.
Where there are differences, these articles generally use the commands in
Berkeley UNIX.
If a command doesn't seem to work on your system, check its online
manual page or the <EM
CLASS="emphasis"
>sh</EM
> manual page.</P
><DIV
CLASS="sect1info"
><P
CLASS="SECT1INFO"
>- <SPAN
CLASS="authorinitials"
>JP</SPAN
></P
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