ch11_07.htm

the unix power tools

CLASS="userinput"
><B
>echo 1 2 3 4 5</B
></CODE
>
1 2 3 4 5
% <CODE
CLASS="userinput"
><B
>echo !*</B
></CODE
>
echo 1 2 3 4 5
1 2 3 4 5</PRE
></BLOCKQUOTE
></P
><P
CLASS="para"
>In an alias:&#13;</P
><P
CLASS="para"
><BLOCKQUOTE
CLASS="screen"
><PRE
CLASS="screen"
>alias vcat 'cat -v \!* | more'</PRE
></BLOCKQUOTE
></P
><P
CLASS="para"
>&#13;will pipe the output of
<SPAN
CLASS="link"
><EM
CLASS="emphasis"
>cat -v</EM
> (<A
CLASS="linkend"
HREF="ch25_07.htm"
TITLE="Show Non-Printing Characters with cat -v or od -c "
>25.7</A
>)</SPAN
>
command through <EM
CLASS="emphasis"
>more</EM
>.
The backslash (<CODE
CLASS="literal"
>\</CODE
>) has to be there to hide the history character,
<CODE
CLASS="literal"
>!</CODE
>,
until the alias is used-see article
<A
CLASS="xref"
HREF="ch10_03.htm"
TITLE="C Shell Aliases with Command-Line Arguments "
>10.3</A
>
for more information.</P
></LI
><LI
CLASS="listitem"
><P
CLASS="para"
><A
CLASS="indexterm"
NAME="AUTOID-12726"
></A
><CODE
CLASS="userinput"
><B
>!:2*</B
></CODE
> gives the second through the last arguments:&#13;</P
><P
CLASS="para"
><BLOCKQUOTE
CLASS="screen"
><PRE
CLASS="screen"
>% <CODE
CLASS="userinput"
><B
>echo 1 2 3 4 5</B
></CODE
>
1 2 3 4 5
% <CODE
CLASS="userinput"
><B
>echo !:2*</B
></CODE
>
echo 2 3 4 5
2 3 4 5</PRE
></BLOCKQUOTE
></P
><P
CLASS="para"
></P
></LI
><LI
CLASS="listitem"
><P
CLASS="para"
><CODE
CLASS="userinput"
><B
>!:2-</B
></CODE
> like <CODE
CLASS="literal"
>2*</CODE
> but the last argument is dropped:&#13;</P
><P
CLASS="para"
><BLOCKQUOTE
CLASS="screen"
><PRE
CLASS="screen"
>% <CODE
CLASS="userinput"
><B
>echo 1 2 3 4 5</B
></CODE
>
1 2 3 4 5
% <CODE
CLASS="userinput"
><B
>echo !:2-</B
></CODE
>
echo 2 3 4
2 3 4</PRE
></BLOCKQUOTE
></P
><P
CLASS="para"
></P
></LI
><LI
CLASS="listitem"
><P
CLASS="para"
><CODE
CLASS="userinput"
><B
>!?fn?%</B
></CODE
> gives the first word found that has <CODE
CLASS="literal"
>fn</CODE
> in it:&#13;</P
><P
CLASS="para"
><BLOCKQUOTE
CLASS="screen"
><PRE
CLASS="screen"
>% <CODE
CLASS="userinput"
><B
>sort fn1 fn2 fn3</B
></CODE
>
       ...
% <CODE
CLASS="userinput"
><B
>echo !?fn?%</B
></CODE
>
echo fn1
fn1</PRE
></BLOCKQUOTE
></P
><P
CLASS="para"
>That found the <CODE
CLASS="literal"
>fn</CODE
> in <CODE
CLASS="literal"
>fn1</CODE
>.
You can get wilder with:&#13;</P
><P
CLASS="para"
><BLOCKQUOTE
CLASS="screen"
><PRE
CLASS="screen"
>% <CODE
CLASS="userinput"
><B
>echo 1 2 3 4 5</B
></CODE
>
1 2 3 4 5
% <CODE
CLASS="userinput"
><B
>echo !?ec?^</B
></CODE
>
echo 1
1</PRE
></BLOCKQUOTE
></P
><P
CLASS="para"
>That selected the command that had <CODE
CLASS="literal"
>ec</CODE
> in it, and the caret (<CODE
CLASS="literal"
>^</CODE
>)
said to give the first argument of that command.
You can also do something like:&#13;</P
><P
CLASS="para"
><BLOCKQUOTE
CLASS="screen"
><PRE
CLASS="screen"
>% <CODE
CLASS="userinput"
><B
>echo fn fn1 fn2</B
></CODE
>
fn fn1 fn2

% <CODE
CLASS="userinput"
><B
>echo !?fn1?^ !$</B
></CODE
>
echo fn fn2
fn fn2</PRE
></BLOCKQUOTE
></P
><P
CLASS="para"
>That cryptic command told the shell to look for a command that had
<CODE
CLASS="literal"
>fn1</CODE
> in it (<CODE
CLASS="literal"
>!?fn1?</CODE
>), and gave the first argument of that
command (<CODE
CLASS="literal"
>^</CODE
>).
Then it gave the last argument (<CODE
CLASS="literal"
>!$</CODE
>).</P
></LI
><LI
CLASS="listitem"
><P
CLASS="para"
><A
CLASS="indexterm"
NAME="AUTOID-12775"
></A
><CODE
CLASS="userinput"
><B
>^xy^yx</B
></CODE
> is the
<SPAN
CLASS="link"
>shorthand substitution (<A
CLASS="linkend"
HREF="ch11_03.htm"
TITLE="My Favorite Is !$ "
>11.3</A
>, <A
CLASS="linkend"
HREF="ch11_05.htm"
TITLE="My Favorite Is ^^ "
>11.5</A
>)</SPAN
>
command.
In the case of:&#13;</P
><P
CLASS="para"
><BLOCKQUOTE
CLASS="screen"
><PRE
CLASS="screen"
>% <CODE
CLASS="userinput"
><B
>echo xxyyzzxx</B
></CODE
>
xxyyzzxx
% <CODE
CLASS="userinput"
><B
>^xx^ab</B
></CODE
>
echo abyyzzxx
abyyzzxx</PRE
></BLOCKQUOTE
></P
><P
CLASS="para"
>it replaced the characters <CODE
CLASS="literal"
>xx</CODE
> with <CODE
CLASS="literal"
>ab</CODE
>.
This makes editing the previous command much easier.</P
></LI
><LI
CLASS="listitem"
><P
CLASS="para"
><CODE
CLASS="userinput"
><B
>!!:s/xx/ab/</B
></CODE
>
is doing the same thing as the previous example, but it is using the
substitute command instead of the <CODE
CLASS="literal"
>^</CODE
>.
This works for any previous command, as in:&#13;</P
><P
CLASS="para"
><BLOCKQUOTE
CLASS="screen"
><PRE
CLASS="screen"
>% <CODE
CLASS="userinput"
><B
>more afile bfile</B
></CODE
>
       ...
% <CODE
CLASS="userinput"
><B
>echo xy</B
></CODE
>
xy
% <CODE
CLASS="userinput"
><B
>!m:s/b/c/</B
></CODE
>
more afile cfile</PRE
></BLOCKQUOTE
></P
><P
CLASS="para"
>You do not have to use the slashes (<CODE
CLASS="literal"
>/</CODE
>); any character can act as a delimiter.&#13;</P
><P
CLASS="para"
><BLOCKQUOTE
CLASS="screen"
><PRE
CLASS="screen"
>% <CODE
CLASS="userinput"
><B
>!!:s:xy:yx</B
></CODE
></PRE
></BLOCKQUOTE
></P
><P
CLASS="para"
>There we used the colons (<CODE
CLASS="literal"
>:</CODE
>) [good when the word you're 
trying to edit contains a slash-<EM
CLASS="emphasis"
>JP</EM
> ].
If you want to add more to the replacement, use <CODE
CLASS="literal"
>&amp;</CODE
> to &quot;replay it&quot; and then add
on whatever you like:&#13;</P
><P
CLASS="para"
><BLOCKQUOTE
CLASS="screen"
><PRE
CLASS="screen"
>% <CODE
CLASS="userinput"
><B
>echo xy</B
></CODE
>
xy
% <CODE
CLASS="userinput"
><B
>!!:s/xy/&amp;yx</B
></CODE
>
echo xyyx
xyyx</PRE
></BLOCKQUOTE
></P
><P
CLASS="para"
>The <CODE
CLASS="literal"
>&amp;</CODE
> in the replacement part said to give what the search
part found, which was the <CODE
CLASS="literal"
>xy</CODE
> characters.</P
><P
CLASS="para"
>The search part, or left side, cannot include
<SPAN
CLASS="link"
>metacharacters (<A
CLASS="linkend"
HREF="ch26_03.htm"
TITLE="Understanding Expressions "
>26.3</A
>)</SPAN
>.
You must type the actual string you are looking for.</P
><P
CLASS="para"
>Also, the example above only replaces the first occurrence of <CODE
CLASS="literal"
>xy</CODE
>.<A
CLASS="indexterm"
NAME="AUTOID-12816"
></A
>
To replace them all, use <EM
CLASS="emphasis"
>g</EM
>:&#13;</P
><P
CLASS="para"
><BLOCKQUOTE
CLASS="screen"
><PRE
CLASS="screen"
>% <CODE
CLASS="userinput"
><B
>echo xy xy xy xy</B
></CODE
>
xy xy xy xy
% <CODE
CLASS="userinput"
><B
>!!:s/xy/yx/</B
></CODE
>
echo yx xy xy xy
yx xy xy xy
% <CODE
CLASS="userinput"
><B
>!!:gs/xy/yx/</B
></CODE
>
echo yx yx yx yx
yx yx yx yx</PRE
></BLOCKQUOTE
></P
><P
CLASS="para"
>The <EM
CLASS="emphasis"
>g</EM
> command in this case meant do all the <CODE
CLASS="literal"
>xy</CODE
>s.
And oddly enough, the <EM
CLASS="emphasis"
>g</EM
> has to come before the <EM
CLASS="emphasis"
>s</EM
> command.</P
><P
CLASS="para"
>Or you could have done:</P
><P
CLASS="para"
><BLOCKQUOTE
CLASS="screen"
><PRE
CLASS="screen"
>% <CODE
CLASS="userinput"
><B
>echo xy xy xy xy</B
></CODE
>
xy xy xy xy
% <CODE
CLASS="userinput"
><B
>!!:s/xy/yx/</B
></CODE
>
echo yx xy xy xy
yx xy xy xy
% <CODE
CLASS="userinput"
><B
>!!:g&amp;</B
></CODE
>
echo yx yx yx yx
yx yx yx yx</PRE
></BLOCKQUOTE
></P
><P
CLASS="para"
>&#13;In that case, we told the shell to globally (<CODE
CLASS="literal"
>:g</CODE
>) replace every
matched string from the last command with the
last substitution (<CODE
CLASS="literal"
>&amp;</CODE
>).
Without the <EM
CLASS="emphasis"
>g</EM
> command, the shells would have replaced just one more 
<CODE
CLASS="literal"
>xy</CODE
> with <CODE
CLASS="literal"
>yx</CODE
>.</P
><P
CLASS="para"
>[A &quot;global&quot; substitution works just once per word:</P
><P
CLASS="para"
><BLOCKQUOTE
CLASS="screen"
><PRE
CLASS="screen"
>% <CODE
CLASS="userinput"
><B
>echo xyzzy</B
></CODE
>
xyzzy
% <CODE
CLASS="userinput"
><B
>!!:gs/y/p/</B
></CODE
>
echo xpzzy
xpzzy</PRE
></BLOCKQUOTE
></P
><P
CLASS="para"
>The substitution above changed only the first <CODE
CLASS="literal"
>y</CODE
>. <EM
CLASS="emphasis"
>-TC</EM
> ]</P
></LI
></UL
><A
CLASS="indexterm"
NAME="AUTOID-12849"
></A
><A
CLASS="indexterm"
NAME="AUTOID-12850"
></A
><DIV
CLASS="sect1info"
><P
CLASS="SECT1INFO"
>- <SPAN
CLASS="authorinitials"
>DR</SPAN
></P
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