ch02_16.htm

the unix power tools

CLASS="literal"
>-tcsh</CODE
>)
unless you have the current directory (<CODE
CLASS="literal"
>.</CODE
>) in your
<SPAN
CLASS="link"
>search path (<A
CLASS="linkend"
HREF="ch08_07.htm"
TITLE="Setting Your Search Path "
>8.7</A
>)</SPAN
>
(put it at the end of your path!).
You may also be able to use an<A
CLASS="indexterm"
NAME="AUTOID-3874"
></A
><A
CLASS="indexterm"
NAME="AUTOID-3876"
></A
>
<SPAN
CLASS="link"
>absolute pathname (<A
CLASS="linkend"
HREF="ch14_02.htm"
TITLE="Using Relative and Absolute Pathnames "
>14.2</A
>)</SPAN
>
to the new shell, but that could hide the leading
minus sign (<CODE
CLASS="literal"
>-</CODE
>) and the shell might not act like a login shell.<A
CLASS="indexterm"
NAME="AUTOID-3881"
></A
><A
CLASS="indexterm"
NAME="AUTOID-3884"
></A
></P
></LI
><LI
CLASS="listitem"
><P
CLASS="para"
>Is there a chance that your new shell might be missing some day?
For instance, is it on a network filesystem that might be unavailable?
Then it's a good idea to wrap the new code above with a test:</P
><P
CLASS="para"
><TABLE
CLASS="screen.co"
BORDER="1"
><TR
><TH
VALIGN="TOP"
><PRE
CLASS="calloutlist"
>
<A
CLASS="co"
HREF="ch47_04.htm"
TITLE="47.4 C Shell Variable Operators and Expressions "
>-e</A
> 


&#13;</PRE
></TH
><TD
VALIGN="TOP"
><PRE
CLASS="screen"
>
if (-e <CODE
CLASS="replaceable"
><I
>my-new-shell</I
></CODE
>) then
    <I
CLASS="lineannotation"
>...code to start new shell...</I
>
else
    echo &quot;*** WARNING: new shell failed.  Using csh. ***&quot;
endif</PRE
></TD
></TR
></TABLE
></P
></LI
></UL
></LI
><LI
CLASS="listitem"
><P
CLASS="para"
>Test your new setup:

<UL
CLASS="itemizedlist"
><LI
CLASS="listitem"
><P
CLASS="para"
>Try commands that start
<SPAN
CLASS="link"
>subshells (<A
CLASS="linkend"
HREF="ch38_04.htm"
TITLE="Subshells "
>38.4</A
>)</SPAN
>,<A
CLASS="indexterm"
NAME="AUTOID-3900"
></A
>
like
<SPAN
CLASS="link"
><EM
CLASS="emphasis"
>su</EM
>, <EM
CLASS="emphasis"
>rsh</EM
>, and so on (<A
CLASS="linkend"
HREF="ch02_07.htm"
TITLE="C Shell Setup Files Aren't Read When You Want Them to Be? "
>2.7</A
>)</SPAN
>,
to be sure that they start your new shell.</P
></LI
><LI
CLASS="listitem"
><P
CLASS="para"
><A
CLASS="indexterm"
NAME="AUTOID-3908"
></A
>Put the <EM
CLASS="emphasis"
>csh</EM
> command
<SPAN
CLASS="link"
><EM
CLASS="emphasis"
>set&nbsp;echo</EM
> (<A
CLASS="linkend"
HREF="ch08_17.htm"
TITLE="verbose and echo Variables Show Quoting "
>8.17</A
>)</SPAN
>
at the top of your <EM
CLASS="emphasis"
>.cshrc</EM
>
file to be sure your commands there are working.</P
></LI
><LI
CLASS="listitem"
><P
CLASS="para"
>Type a command that will work only in your new shell (not in a C shell).</P
></LI
><LI
CLASS="listitem"
><P
CLASS="para"
><A
CLASS="indexterm"
NAME="AUTOID-3918"
></A
>Use the
<SPAN
CLASS="link"
><EM
CLASS="emphasis"
>ps</EM
> (<A
CLASS="linkend"
HREF="ch38_05.htm"
TITLE="The ps Command "
>38.5</A
>)</SPAN
>
command
<CODE
CLASS="literal"
>ps</CODE
>&nbsp;<CODE
CLASS="literal"
>$$</CODE
> (on System V, <CODE
CLASS="literal"
>ps</CODE
>&nbsp;<CODE
CLASS="literal"
>-f</CODE
>&nbsp;<CODE
CLASS="literal"
>-p</CODE
>&nbsp;<CODE
CLASS="literal"
>$$</CODE
>)
to look at your new shell process (<CODE
CLASS="literal"
>$$</CODE
> is your shell's
<SPAN
CLASS="link"
>process ID number (<A
CLASS="linkend"
HREF="ch38_03.htm"
TITLE="Managing Processes: Overall Concepts "
>38.3</A
>)</SPAN
>).</P
></LI
><LI
CLASS="listitem"
><P
CLASS="para"
><SPAN
CLASS="link"
> Before you log out of this shell, try logging in from somewhere else  (<A
CLASS="linkend"
HREF="ch02_04.htm"
TITLE="Tip for Changing Account Setup: Keep a Shell Ready "
>2.4</A
>)</SPAN
>
to be sure your new shell startup files work.</P
></LI
></UL
>&#13;</P
></LI
><LI
CLASS="listitem"
><P
CLASS="para"
>You're set to go.</P
></LI
></OL
><P
CLASS="para"
>If your login shell isn't listed in <EM
CLASS="emphasis"
>/etc/shells</EM
>, the
<SPAN
CLASS="link"
><EM
CLASS="emphasis"
>ftp</EM
> (<A
CLASS="linkend"
HREF="ch52_07.htm"
TITLE="Other Ways to Get the Software "
>52.7</A
>)</SPAN
>
program<A
CLASS="indexterm"
NAME="AUTOID-3939"
></A
><A
CLASS="indexterm"
NAME="AUTOID-3941"
></A
><A
CLASS="indexterm"
NAME="AUTOID-3943"
></A
>
(actually, the <EM
CLASS="emphasis"
>ftpd</EM
>
<SPAN
CLASS="link"
>daemon (<A
CLASS="linkend"
HREF="ch01_14.htm"
TITLE="The Kernel and Daemons "
>1.14</A
>)</SPAN
>)
may refuse to transfer files to your account.
That's partly to stop <EM
CLASS="emphasis"
>ftp</EM
> access to your system through special accounts
that don't have passwords, like <EM
CLASS="emphasis"
>sync</EM
>, <EM
CLASS="emphasis"
>who</EM
>, <EM
CLASS="emphasis"
>finger</EM
>, and so on.
If you use the workaround steps above, though, that shouldn't be a problem;
you'll have an approved shell listed in <EM
CLASS="emphasis"
>/etc/passwd</EM
> and <EM
CLASS="emphasis"
>ftp</EM
>
usually doesn't run your login shell, anyway.</P
><A
CLASS="indexterm"
NAME="AUTOID-3954"
></A
><A
CLASS="indexterm"
NAME="AUTOID-3955"
></A
><A
CLASS="indexterm"
NAME="AUTOID-3956"
></A
><DIV
CLASS="sect1info"
><P
CLASS="SECT1INFO"
>- <SPAN
CLASS="authorinitials"
>JP</SPAN
></P
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