ch34_24.htm

the unix power tools

><P
CLASS="para"
></P
></DD
><DT
CLASS="term"
><CODE
CLASS="literal"
>c</CODE
></DT
><DD
CLASS="listitem"
><P
CLASS="para"
><BLOCKQUOTE
CLASS="literallayout"
><P
CLASS="literallayout"
><CODE
CLASS="literal"
>[</CODE
><CODE
CLASS="replaceable"
><I
>address1</I
></CODE
>][<CODE
CLASS="literal"
>,</CODE
><CODE
CLASS="replaceable"
><I
>address2</I
></CODE
><CODE
CLASS="literal"
>]c\</CODE
><BR><CODE
CLASS="replaceable"
><I
>text</I
></CODE
></P
></BLOCKQUOTE
></P
><P
CLASS="para"
>Replace the lines selected by the address with <CODE
CLASS="replaceable"
><I
>text</I
></CODE
>.
When a range of lines is specified, all lines as a group are replaced
by a single copy of <CODE
CLASS="replaceable"
><I
>text</I
></CODE
>.
The newline following each line of <CODE
CLASS="replaceable"
><I
>text</I
></CODE
> must be escaped by
a backslash, except the last line.
The contents of the pattern space are, in effect, deleted and
no subsequent editing commands can be applied to it (or <CODE
CLASS="replaceable"
><I
>text</I
></CODE
>).</P
><P
CLASS="para"
><EM
CLASS="emphasis"
>Example</EM
></P
><P
CLASS="para"
><BLOCKQUOTE
CLASS="screen"
><PRE
CLASS="screen"
># Replace first 100 lines in a file:
1,100c\
<I
CLASS="lineannotation"
>...first replacement line</I
>\
<I
CLASS="lineannotation"
>...second replacement line</I
>\
<I
CLASS="lineannotation"
>...</I
>\
<I
CLASS="lineannotation"
>...last replacement line</I
></PRE
></BLOCKQUOTE
></P
><P
CLASS="para"
></P
></DD
><DT
CLASS="term"
><CODE
CLASS="literal"
>d</CODE
></DT
><DD
CLASS="listitem"
><P
CLASS="para"
><CODE
CLASS="literal"
>[</CODE
><CODE
CLASS="replaceable"
><I
>address1</I
></CODE
><CODE
CLASS="literal"
>][,</CODE
><CODE
CLASS="replaceable"
><I
>address2</I
></CODE
><CODE
CLASS="literal"
>]d</CODE
></P
><P
CLASS="para"
>Delete the addressed line (or lines) from the pattern space. Thus, the 
line is not passed to standard
output. A new line of input is read, and editing resumes with the first
command in the script.
See articles
<A
CLASS="xref"
HREF="ch34_04.htm"
TITLE="sed Addressing Basics "
>34.4</A
>
and
<A
CLASS="xref"
HREF="ch34_18.htm"
TITLE="Multiline Delete "
>34.18</A
>.</P
><P
CLASS="para"
><EM
CLASS="emphasis"
>Example</EM
></P
><P
CLASS="para"
><BLOCKQUOTE
CLASS="screen"
><PRE
CLASS="screen"
># delete all blank lines:
/^$/d</PRE
></BLOCKQUOTE
></P
></DD
><DT
CLASS="term"
><CODE
CLASS="literal"
>D</CODE
></DT
><DD
CLASS="listitem"
><P
CLASS="para"
>[<CODE
CLASS="replaceable"
><I
>address1</I
></CODE
>][<CODE
CLASS="literal"
>,</CODE
><CODE
CLASS="replaceable"
><I
>address2</I
></CODE
>]<CODE
CLASS="literal"
>D</CODE
></P
><P
CLASS="para"
>Delete first part (up to embedded newline) of multiline pattern space created
by <EM
CLASS="emphasis"
>N</EM
> command and resume editing with first command in
script. If this command empties the pattern space, then a new line
of input is read, as if <EM
CLASS="emphasis"
>d</EM
> had been executed.
See article <A
CLASS="xref"
HREF="ch34_18.htm"
TITLE="Multiline Delete "
>34.18</A
>.</P
><P
CLASS="para"
><EM
CLASS="emphasis"
>Example</EM
></P
><P
CLASS="para"
><BLOCKQUOTE
CLASS="screen"
><PRE
CLASS="screen"
># Strip multiple blank lines, leaving only one:
/^$/{
    N
    /^\n$/D
}</PRE
></BLOCKQUOTE
></P
></DD
><DT
CLASS="term"
><CODE
CLASS="literal"
>g</CODE
></DT
><DD
CLASS="listitem"
><P
CLASS="para"
><CODE
CLASS="literal"
>[</CODE
><CODE
CLASS="replaceable"
><I
>address1</I
></CODE
><CODE
CLASS="literal"
>][,</CODE
><CODE
CLASS="replaceable"
><I
>address2</I
></CODE
><CODE
CLASS="literal"
>]g</CODE
></P
><P
CLASS="para"
>Paste the contents of the hold space (see <EM
CLASS="emphasis"
>h</EM
> or <EM
CLASS="emphasis"
>H</EM
>) back
into the pattern space, wiping out the previous contents of the pattern space.
See articles <A
CLASS="xref"
HREF="ch34_13.htm"
TITLE="Hold Space: The Set-Aside Buffer "
>34.13</A
> and <A
CLASS="xref"
HREF="ch34_16.htm"
TITLE="The Deliberate Scrivener "
>34.16</A
>.
The example shows a simple way to copy lines.</P
><P
CLASS="para"
><EM
CLASS="emphasis"
>Example</EM
></P
><P
CLASS="para"
>This script collects all lines containing the word <CODE
CLASS="literal"
>Item:</CODE
>
and copies them to a place marker later in the file.
The place marker is overwritten.</P
><P
CLASS="para"
><BLOCKQUOTE
CLASS="screen"
><PRE
CLASS="screen"
>/Item:/H
/&lt;Replace this line with the item list&gt;/g</PRE
></BLOCKQUOTE
></P
><P
CLASS="para"
></P
></DD
><DT
CLASS="term"
><CODE
CLASS="literal"
>G</CODE
></DT
><DD
CLASS="listitem"
><P
CLASS="para"
>[<CODE
CLASS="replaceable"
><I
>address1</I
></CODE
>][<CODE
CLASS="literal"
>,</CODE
><CODE
CLASS="replaceable"
><I
>address2</I
></CODE
>]<CODE
CLASS="literal"
>G</CODE
></P
><P
CLASS="para"
>Same as <EM
CLASS="emphasis"
>g</EM
>, except that the hold space is pasted below the address
instead of overwriting it.
The example shows a simple way to &quot;cut and paste&quot; lines.
See articles <A
CLASS="xref"
HREF="ch34_13.htm"
TITLE="Hold Space: The Set-Aside Buffer "
>34.13</A
> and <A
CLASS="xref"
HREF="ch34_16.htm"
TITLE="The Deliberate Scrivener "
>34.16</A
>.</P
><P
CLASS="para"
><EM
CLASS="emphasis"
>Example</EM
></P
><P
CLASS="para"
>This script collects all lines containing the word <CODE
CLASS="literal"
>Item:</CODE
>
and moves them after a place marker later in the file.
The original <CODE
CLASS="literal"
>Item:</CODE
> lines are deleted.</P
><P
CLASS="para"
><BLOCKQUOTE
CLASS="screen"
><PRE
CLASS="screen"
>/Item:/{
    H
    d
}
/Summary of items:/G</PRE
></BLOCKQUOTE
></P
><P
CLASS="para"
></P
></DD
><DT
CLASS="term"
><CODE
CLASS="literal"
>h</CODE
></DT
><DD
CLASS="listitem"
><P
CLASS="para"
>[<CODE
CLASS="replaceable"
><I
>address1</I
></CODE
>][<CODE
CLASS="literal"
>,</CODE
><CODE
CLASS="replaceable"
><I
>address2</I
></CODE
>]<CODE
CLASS="literal"
>h</CODE
>

Copy the pattern space into the hold space, a special temporary buffer.
The previous contents of the hold space are obliterated.
You can use <EM
CLASS="emphasis"
>h</EM
> to save a line before editing it.
See articles <A
CLASS="xref"
HREF="ch34_13.htm"
TITLE="Hold Space: The Set-Aside Buffer "
>34.13</A
> and <A
CLASS="xref"
HREF="ch34_16.htm"
TITLE="The Deliberate Scrivener "
>34.16</A
>.</P
><P
CLASS="para"
><EM
CLASS="emphasis"
>Example</EM
></P
><P
CLASS="para"
><BLOCKQUOTE
CLASS="screen"
><PRE
CLASS="screen"
># Edit a line; print the change; replay the original
/UNIX/{
    h
    s/.* UNIX \(.*\) .*/\1:/
    p
    x
}</PRE
></BLOCKQUOTE
></P
><P
CLASS="para"
><EM
CLASS="emphasis"
>Sample input:</EM
></P
><P
CLASS="para"
><BLOCKQUOTE
CLASS="screen"
><PRE
CLASS="screen"
>This describes the UNIX ls command.
This describes the UNIX cp command.</PRE
></BLOCKQUOTE
></P
><P
CLASS="para"
><EM
CLASS="emphasis"
>Sample output:</EM
></P
><P
CLASS="para"
><BLOCKQUOTE
CLASS="screen"
><PRE
CLASS="screen"
>ls:
This describes the UNIX ls command.
cp:
This describes the UNIX cp command.</PRE
></BLOCKQUOTE
></P
><P
CLASS="para"
>&#13;</P
></DD
><DT
CLASS="term"
><CODE
CLASS="literal"
>H</CODE
></DT
><DD
CLASS="listitem"
><P
CLASS="para"
>[<CODE
CLASS="replaceable"
><I
>address1</I
></CODE
>][<CODE
CLASS="literal"
>,</CODE
><CODE
CLASS="replaceable"
><I
>address2</I
></CODE
>]<CODE
CLASS="literal"
>H</CODE
></P
><P
CLASS="para"
>Append the contents of the pattern space (preceded by a newline)
to the contents of the hold space. Even if the hold space is empty,
<EM
CLASS="emphasis"
>H</EM
> still appends a newline. <EM
CLASS="emphasis"
>H</EM
> is like an incremental copy.
See examples under <EM
CLASS="emphasis"
>g</EM
> and <EM
CLASS="emphasis"
>G</EM
>,
also articles
<A
CLASS="xref"
HREF="ch34_13.htm"
TITLE="Hold Space: The Set-Aside Buffer "
>34.13</A
>
and
<A
CLASS="xref"
HREF="ch34_16.htm"
TITLE="The Deliberate Scrivener "
>34.16</A
>.&#13;</P
></DD
><DT
CLASS="term"
><CODE
CLASS="literal"
>i</CODE
></DT
><DD
CLASS="listitem"
><P
CLASS="para"
><BLOCKQUOTE
CLASS="literallayout"
><P
CLASS="literallayout"
><CODE
CLASS="literal"
>[</CODE
><CODE
CLASS="replaceable"
><I
>address</I
></CODE
><CODE
CLASS="literal"
>]i\</CODE
><BR><CODE
CLASS="replaceable"
><I
>text</I
></CODE
> </P
></BLOCKQUOTE
>
Insert <CODE
CLASS="replaceable"
><I
>text</I
></CODE
> before each line matched by <CODE
CLASS="replaceable"
><I
>address</I
></CODE
>.
(See <EM
CLASS="emphasis"
>a</EM
> for details on <CODE
CLASS="replaceable"
><I
>text</I
></CODE
>.)
Article
<A
CLASS="xref"
HREF="ch43_20.htm"
TITLE="Displaying a troff Macro Definition "
>43.20</A
>
shows a script that uses <EM
CLASS="emphasis"
>i</EM
>.</P
><P
CLASS="para"
><EM
CLASS="emphasis"
>Example</EM
></P
><P
CLASS="para"
><BLOCKQUOTE
CLASS="screen"
><PRE
CLASS="screen"
>/Item 1/i\
The five items are listed below:</PRE
></BLOCKQUOTE
></P
><P
CLASS="para"
></P
></DD
><DT
CLASS="term"
><CODE
CLASS="literal"
>l</CODE
></DT
><DD
CLASS="listitem"
><P
CLASS="para"
>[<CODE
CLASS="replaceable"
><I
>address1</I
></CODE
>][<CODE
CLASS="literal"
>,</CODE
><CODE
CLASS="replaceable"
><I
>address2</I
></CODE
>]<CODE
CLASS="literal"
>l</CODE
></P
><P
CLASS="para"
>List the contents of the pattern space, showing non-printing
characters as
<SPAN
CLASS="link"
>ASCII codes (<A
CLASS="linkend"
HREF="ch51_03.htm"
TITLE="ASCII Characters: Listing and Getting Values "
>51.3</A
>, <A
CLASS="linkend"
HREF="ch25_07.htm"
TITLE="Show Non-Printing Characters with cat -v or od -c "
>25.7</A
>)</SPAN
>.
Long lines are wrapped.</P
></DD
><DT
CLASS="term"
><CODE
CLASS="literal"
>n</CODE
></DT
><DD
CLASS="listitem"
><P
CLASS="para"
>[<CODE
CLASS="replaceable"
><I
>address1</I
></CODE
>][<CODE
CLASS="literal"
>,</CODE
><CODE
CLASS="replaceable"
><I
>address2</I
></CODE
>]<CODE
CLASS="literal"
>n</CODE
></P
><P
CLASS="para"
>Read next line of input into pattern space. The current line is sent to
standard output, and the next line becomes the current line.
Control passes to the command following <EM
CLASS="emphasis"
>n</EM
> instead of resuming at the top
of the script.</P
><P
CLASS="para"
><EM
CLASS="emphasis"
>Example</EM
></P
><P
CLASS="para"
>In the
<SPAN
CLASS="link"
><EM
CLASS="emphasis"
>ms</EM
> macros (<A
CLASS="linkend"
HREF="ch43_14.htm"
TITLE="nroff/troff and Macro Packages "
>43.14</A
>)</SPAN
>,
a section header occurs on the line
below an <CODE
CLASS="literal"
>.NH</CODE
> macro. To print all lines of header text, invoke this
script with <EM
CLASS="emphasis"
>sed -n</EM
>:</P
><P
CLASS="para"
><BLOCKQUOTE
CLASS="screen"
><PRE
CLASS="screen"
>/^\.NH/{
    n
    p
}<A
CLASS="indexterm"
NAME="AUTOID-39783"
></A
></PRE
></BLOCKQUOTE
></P
><P
CLASS="para"
></P
></DD
><DT
CLASS="term"
><CODE
CLASS="literal"
>N</CODE
></DT
><DD
CLASS="listitem"
><P
CLASS="para"
>[<CODE
CLASS="replaceable"
><I
>address1</I
></CODE
>][<CODE
CLASS="literal"
>,</CODE
><CODE
CLASS="replaceable"
><I
>address2</I
></CODE
>]<CODE
CLASS="literal"
>N</CODE
></P
><P
CLASS="para"
>Append next input line to contents of pattern space; the two lines are
separated by an embedded newline.
(This command is designed to allow pattern matches across two
lines.) Using <CODE
CLASS="literal"
>\n</CODE
> to match the embedded newline, you can match
patterns across multiple lines. See example under <EM
CLASS="emphasis"
>D</EM
>, also article
<A
CLASS="xref"
HREF="ch34_15.htm"
TITLE="Making Edits Across Line Boundaries "
>34.15</A
>.</P
><P
CLASS="para"
><EM
CLASS="emphasis"
>Examples</EM
></P
><P
CLASS="para"
>Like previous example, but print <CODE
CLASS="literal"
>.NH</CODE
> line as well as header title:</P
><P
CLASS="para"
><BLOCKQUOTE
CLASS="screen"
><PRE
CLASS="screen"
>/^\.NH/{
    N
    p
}</PRE
></BLOCKQUOTE
></P
><P
CLASS="para"
>Join two lines (replace newline with space):</P
><P
CLASS="para"
><BLOCKQUOTE
CLASS="screen"
><PRE
CLASS="screen"
>/^\.NH/{
    N
    s/\n/ /
    p
}</PRE
></BLOCKQUOTE
></P
></DD
><DT
CLASS="term"
><CODE
CLASS="literal"
>p</CODE
></DT
><DD
CLASS="listitem"
><P
CLASS="para"
>[<CODE
CLASS="replaceable"
><I
>address1</I
></CODE
>][<CODE
CLASS="literal"
>,</CODE
><CODE
CLASS="replaceable"
><I
>address2</I
></CODE
>]<CODE
CLASS="literal"
>p</CODE
></P
><P
CLASS="para"
>Print the addressed line(s). Unless the <EM
CLASS="emphasis"
>-n</EM
> command-line
option is used, this command will cause duplicate lines to be
output. Also, it is typically used before commands that
change flow control (<EM
CLASS="emphasis"
>d</EM
>, <EM
CLASS="emphasis"
>N</EM
>, <EM
CLASS="emphasis"
>b</EM
>) and that might
prevent the current line from being output.
See examples under <EM
CLASS="emphasis"
>h</EM
>, <EM
CLASS="emphasis"
>n</EM
>, and <EM
CLASS="emphasis"
>N</EM
>.</P
></DD
><DT
CLASS="term"
><CODE
CLASS="literal"
>P</CODE
></DT
><DD
CLASS="listitem"
><P
CLASS="para"
>[<CODE
CLASS="replaceable"
><I
>address1</I
></CODE
>][<CODE
CLASS="literal"
>,</CODE
><CODE
CLASS="replaceable"
><I
>address2</I
></CODE
>]<CODE
CLASS="literal"
>P</CODE
></P
><P
CLASS="para"
>Print first part (up to embedded newline) of multiline pattern created
by <EM
CLASS="emphasis"