ibm-information-center/dist/eclipse/plugins/i5OS.ic.rzahz_5.4.0.1/sed.htm

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<h2>sed - Stream editor</h2>
<p><strong>Synopsis</strong></p>
<p><img src="delta.gif" alt="Start of change">
<strong>sed [-an] [-C</strong> <em>ccsid</em> <strong>]</strong>
<em>command file</em> ...</p>
<p><strong>sed [-an] [-C</strong> <em>ccsid</em> <strong>] [-e</strong>
<em>command</em><strong>] [-f</strong> <em>command_file</em><strong>]</strong>
<em>file ...</em>
<img src="deltaend.gif" alt="End of change"></p>
<p><strong>Description</strong></p>
<p>The <strong>sed</strong> utility reads the specified <em>
files</em>, or the standard input if no files are specified,
modifying the input as specified by a list of <em>commands</em>.
The input is then written to the standard output.</p>
<p>A single <em>command</em> may be specified as the first argument
to <strong>sed</strong>. Multiple commands may be specified by
using the <strong>-e</strong> or <strong>-f</strong> options. All
commands are applied to the input in the order they are specified
regardless of their origin.</p>
<p><strong>Options</strong></p>
<dl>
<dt><strong>-a</strong></dt>
<dd>By default, the files listed as parameters for the <strong>
w</strong> functions are created (or truncated) before any
processing begins. The <strong>-a</strong> option causes <strong>
sed</strong> to delay opening each file until a command containing
the related <strong>w</strong> function is applied to a line of
input.</dd>
<dt><img src="delta.gif" alt="Start of change"><strong>-C</strong> <em>ccsid</em></dt>
<dd>Any files created by <strong>sed</strong> are created with the CCSID specified by
<em>ccsid</em>. This option overrides the value of the QIBM_CCSID environment
variable.<img src="deltaend.gif" alt="End of change"></dd>
<dt><strong>-e</strong> <em>command</em></dt>
<dd>Append the editing commands specified by the <em>command</em>
argument to the list of commands.</dd>
<dt><strong>-f</strong> <em>command_file</em></dt>
<dd>Append the editing commands found in the file <em>
command_file</em> to the list of commands. The editing commands
should each be listed on a separate line.</dd>
<dt><strong>-n</strong></dt>
<dd>By default, each line of input is echoed to the standard output
after all of the commands have been applied to it. The <strong>
-n</strong> option suppresses this behavior.</dd>
</dl>
<p><strong>Operands</strong></p>
<p>The form of a <strong>sed</strong> command is as follows:</p>
<pre>
[<em>address</em>[,<em>address</em>]]<em>function</em>[<em>arguments</em>]
</pre>
White space may be inserted before the first <em>address</em> and
the <em>function</em> portions of the command.
<p>Normally, <strong>sed</strong> cyclically copies a line of
input, not including its terminating newline character, into a
"pattern space", (unless there is something left after a <strong>
D</strong> function), applies all of the commands with addresses
that select that pattern space, copies the pattern space to the
standard output, appending a newline, and deletes the pattern
space.</p>
<p>Some of the functions use a "hold space" to save all or part of
the pattern space for subsequent retrieval.</p>
<p><strong>Extended Description</strong></p>
<p><strong><em>sed Addresses</em></strong></p>
<p>An address is not required, but if specified must be:</p>
<ul>
<li>a number that counts input lines cumulatively across input
files,</li>
<li>a dollar ($) character that addresses the last line of input,
or</li>
<li>a context address which consists of a regular expression
preceded and followed by a delimiter.</li>
</ul>
<p>A command line with no addresses selects every pattern
space.</p>
<p>A command line with one address selects all of the pattern
spaces that match the address.</p>
<p>A command line with two addresses selects the inclusive range
from the first pattern space that matches the first address through
the next pattern space that matches the second. If the second
address is a number less than or equal to the line number first
selected, only that line is selected. Starting at the first line
following the selected range, <strong>sed</strong> starts looking
again for the first address.</p>
<p>Editing commands can be applied to non-selected pattern spaces
by use of the exclamation character (!) function.</p>
<p><strong><em>sed Regular Expressions</em></strong></p>
<p><strong>sed</strong> regular expressions are basic regular
expressions. In addition, <strong>sed</strong> has the following
two additions to basic regular expressions:</p>
<ul>
<li>In a context address, any character other than a backslash (\)
or newline character may be used to delimit the regular expression.
Also, putting a backslash character before the delimiting character
causes the character to be treated literally. For example, in the
context address <em>\xabc\xdefx</em>, the regular expression
delimiter is an <em>x</em> and the second <em>x</em> stands for
itself, so that the regular expression is <em>abcxdef</em> .</li>
<li>The escape sequence \n matches a newline character embedded in
the pattern space. You can't, however, use a literal newline
character in an address or in the substitute command.</li>
</ul>
<p>One special feature of <strong>sed</strong> regular expressions
is that they can default to the last regular expression used. If a
regular expression is empty, that is, just the delimiter characters are
specified, the last regular expression encountered is used instead.
The last regular expression is defined as the last regular
expression used as part of an address or substitute command, and at
run-time, not compile-time. For example, the command:</p>
<pre>
/abc/s//XXX/
</pre>
<p>will substitute XXX for the pattern abc.</p>
<p><strong><em>sed Functions</em></strong></p>
<p>In the following list of commands, the maximum number of
permissible addresses for each command is indicated by
[<em>0addr</em>], [<em>1addr</em>], or [<em>2addr</em>],
representing zero, one, or two addresses.</p>
<p>The argument <em>text</em> consists of one or more lines. To
embed a newline in the text, precede it with a backslash. Other
backslashes in <em>text</em> are deleted and the following
character taken literally.</p>
<p>The <strong>r</strong> and <strong>w</strong> functions take an
optional <em>file</em> parameter, which should be separated from
the function letter by white space. Each file given as an argument
to <strong>sed</strong> is created (or its contents truncated)
before any input processing begins.</p>
<p>The <strong>b</strong>, <strong>r</strong>,<strong>s</strong>,
<strong>
t</strong>,<strong>w</strong>,<strong>y</strong>,<strong>!</strong>
, and <strong>&amp;</strong> functions all accept additional
arguments. The following synopses indicate which arguments have to
be separated from the function letters by white space
characters.</p>
<p>Two of the functions take a <em>function-list</em>. This is a
list of <strong>sed</strong> functions separated by newlines, as
follows:</p>
<pre>
{ function
function
...
function
}
</pre>
<p>The <strong>{</strong> can be preceded by white space and can be
followed by white space. The function can be preceded by white
space. The terminating <strong>}</strong> must be preceded by a
newline or optional white space.</p>
<dl>
<dt><strong>[<em>2addr</em>] <em>function-list</em></strong></dt>
<dd>Execute <em>function-list</em> only when the pattern space is
selected.</dd>
<dt><strong>[<em>1addr</em>]a\ <em>text</em></strong></dt>
<dd>Write <em>text</em> to standard output immediately before each
attempt to read a line of input, whether by executing the <strong>
N</strong> function or by beginning a new cycle.</dd>
<dt><strong>[<em>2addr</em>]b[<em>label</em>]</strong></dt>
<dd>Branch to the <strong>&amp;</strong> function with the
specified <em>label</em>. If the <em>label</em> is not specified,
branch to the end of the script.</dd>
<dt><strong>[<em>2addr</em>]c\ <em>text</em></strong></dt>
<dd>Delete the pattern space. With 0 or 1 address or at the end of
a 2-address range, <em>text</em> is written to the standard
output.</dd>
<dt><strong>[<em>2addr</em>]d</strong></dt>
<dd>Delete the pattern space and start the next cycle.</dd>
<dt><strong>[<em>2addr</em>]D</strong></dt>
<dd>Delete the initial segment of the pattern space through the
first newline character and start the next cycle.</dd>
<dt><strong>[<em>2addr</em>]g</strong></dt>
<dd>Replace the contents of the pattern space with the contents of
the hold space.</dd>
<dt><strong>[<em>2addr</em>]G</strong></dt>
<dd>Append a newline character followed by the contents of the hold
space to the pattern space.</dd>
<dt><strong>[<em>2addr</em>]h</strong></dt>
<dd>Replace the contents of the hold space with the contents of the
pattern space.</dd>
<dt><strong>[<em>2addr</em>]H</strong></dt>
<dd>Append a newline character followed by the contents of the
pattern space to the hold space.</dd>
<dt><strong>[<em>1addr</em>]i\ <em>text</em></strong></dt>
<dd>Write <em>text</em> to the standard output.</dd>
<dt><strong>[<em>2addr</em>]l</strong></dt>
<dd>(The letter ell.) Write the pattern space to the standard
output in a visually unambiguous form. This form is as follows:
<ul>
<li>backslash (\)</li>
<li>alert (\a)</li>
<li>form-feed (\f)</li>
<li>newline (\n)</li>
<li>carriage-return (\r)</li>
<li>tab (\t)</li>
<li>vertical tab (\v)</li>
</ul>
<p>Nonprintable characters are written as three-digit octal numbers
(with a preceding backslash) for each byte in the character (most
significant byte first). Long lines are folded, with the point of
folding indicated by displaying a backslash followed by a newline.
The end of each line is marked with a dollar sign ($).</p>
</dd>
<dt><strong>[<em>2addr</em>]n</strong></dt>
<dd>Write the pattern space to the standard output if the default
output has not been suppressed, and replace the pattern space with
the next line of input.</dd>
<dt><strong>[<em>2addr</em>]N</strong></dt>
<dd>Append the next line of input to the pattern space, using an
embedded newline character to separate the appended material from
the original contents. Note that the current line number
changes.</dd>
<dt><strong>[<em>2addr</em>]p</strong></dt>
<dd>Write the pattern space to standard output.</dd>
<dt><strong>[<em>2addr</em>]P</strong></dt>
<dd>Write the pattern space, up to the first newline character to
the standard output.</dd>
<dt><strong>[<em>1addr</em>]q</strong></dt>
<dd>Branch to the end of the script and quit without starting a new
cycle.</dd>
<dt><strong>[<em>1addr</em>]r <em>file</em></strong></dt>
<dd>Copy the contents of <em>file</em> to the standard output
immediately before the next attempt to read a line of input. If
<em>file</em> cannot be read for any reason, it is silently ignored
and no error condition is set.</dd>
<dt><strong>
[<em>2addr</em>]s/<em>regular_expression</em>/<em>replacement</em>/<em>
flags</em></strong></dt>
<dd>Substitute the <em>replacement</em> string for the first
instance of the <em>regular_expression</em> in the pattern space.
Any character other than backslash or newline can be used instead
of a slash to delimit the <em>regular_expression</em> and the <em>
replacement</em>. Within the <em>regular_expression</em> and the
<em>replacement</em>, the regular expression delimiter itself can
be used as a literal character if it is preceded by a backslash.
<p>An ampersand (&amp;) appearing in the <em>replacement</em> is
replaced by the string matching the regular expression. The special
meaning of &amp; in this context can be suppressed by preceding it
by a backslash. The string \#, where # is a digit, is replaced by
the text matched by the corresponding backreference expression.</p>
<p>A line can be split by substituting a newline character into it.
To specify a newline character in the replacement string, precede
it with a backslash.</p>
<p>The value of <em>flags</em> in the substitute function is zero
or more of the following:</p>
<dl>
<dt><strong>0 ... 9</strong></dt>
<dd>Make the substitution only for the N'th occurrence of the
regular expression in the pattern space.</dd>
<dt><strong>g</strong></dt>
<dd>Make the substitution for all non-overlapping matches of the
regular expression, not just the first one.</dd>
<dt><strong>p</strong></dt>
<dd>Write the pattern space to standard output if a replacement was
made. If the replacement string is identical to that which it
replaces, it is still considered to have been a replacement.</dd>
<dt><strong>w <em>file</em></strong></dt>
<dd>Append the pattern space to <em>file</em> if a replacement was
made. If the replacement string is identical to that which it
replaces, it is still considered to have been a replacement.</dd>
</dl>
</dd>
<dt><strong>[<em>2addr</em>]t [<em>label</em>]</strong></dt>
<dd>Branch to the <strong>:</strong> function bearing the <em>
label</em> if any substitutions have been made since the most
recent reading of an input line or execution of a <strong>
t</strong> function. If no <em>label</em> is specified, branch to
the end of the script.</dd>
<dt><strong>[<em>2addr</em>]w <em>file</em></strong></dt>
<dd>Append the pattern space to the <em>file</em>.</dd>
<dt><strong>[<em>2addr</em>]x</strong></dt>
<dd>Swap the contents of the pattern and hold spaces.</dd>
<dt><strong>
[<em>2addr</em>]y/<em>string1</em>/<em>string2</em>/</strong></dt>
<dd>Replace all occurrences of characters in <em>string1</em> in
the pattern space with the corresponding characters from <em>
string2</em>. Any character other than a backslash or newline can
be used instead of a slash to delimit the strings. Within <em>
string1</em> and <em>string2</em>, a backslash followed by any
character other than a newline is that literal character, and a
<strong>/n</strong> is replaced by a newline character.</dd>
<dt><strong>[<em>2addr</em>]!<em>function</em></strong></dt>
<dt><strong>[<em>2addr</em>]!<em>function-list</em></strong></dt>
<dd>Apply the <em>function</em> or <em>function-list</em> only to
the lines that are <strong>not</strong> selected by the
address(es).</dd>
<dt><strong>[<em>0addr</em>]:<em>label</em></strong></dt>
<dd>This function does nothing; it bears a <em>label</em> to which
the <strong>b</strong> and <strong>t</strong> commands may
branch.</dd>
<dt><strong>[<em>1addr</em>]=</strong></dt>
<dd>Write the line number to the standard output followed by a
newline character.</dd>
<dt><strong>[<em>0addr</em>]</strong></dt>
<dd>Empty lines are ignored.</dd>
<dt><strong>[<em>0addr</em>]#</strong></dt>
<dd>The <strong>#</strong> and the remainder of the line are
ignored (treated as a comment), with the single exception that if
the first two characters in the file are <strong>#n</strong>, the
default output is suppressed. This is the same as specifying the -n
option on the command line.</dd>
</dl>
<p><strong>Environment Variables</strong></p>
<p><strong>sed</strong> is affected by the following environment
variables:</p>
<dl>
<dt><strong>QIBM_CCSID</strong></dt>
<dd>Any files created by <strong>sed</strong> are created with the CCSID specified by
the value of the environment variable.</dd>
</dl>
<p><strong>Exit Status</strong></p>
<ul>
<li>0 on success</li>
<li>&gt;0 if an error occurs</li>
</ul>
<p><strong>Related information</strong></p>
<ul>
<li><a href="cmp.htm">cmp - Compare two files</a></li>
<li><a href="sort.htm">sort - Sort, merge, or sequence check text
files</a></li>
<li><a href="split.htm">split - Split files into pieces</a></li>
<li><a href="uniq.htm">uniq - Report or filter out repeated lines
in a file</a></li>
</ul>
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