$ echo '# Host 1
host 45583 {
filename "junk1.cm";
hardware ethernet 11:42:a3:d4:55:83;
fixed-address 10.100.34.114;
}
# Host 2
host D78C3 {
filename "junk5.cm";
fixed-address 10.100.34.117;
hardware ethernet 11:42:a3:FD:78:C3;
}
# Host 3
host 3A684 {
filename "junk6.cm";
fixed-address 10.100.34.119;
hardware ethernet 11:42:a3:13:a6:84;
}
# Host 4
host 46d54 {
filename "junk4.cm";
fixed-address 10.100.34.120;
hardware ethernet 23:10:3d:14:6d:54;
}
' | perl -e'
$/ = "}\n";
while ( <> ) {
    s/(fixed-address.*\n)(hardware ethernet.*\n)/$2$1/;
    print;
    }
'
# Host 1
host 45583 {
filename "junk1.cm";
hardware ethernet 11:42:a3:d4:55:83;
fixed-address 10.100.34.114;
}
# Host 2
host D78C3 {
filename "junk5.cm";
hardware ethernet 11:42:a3:FD:78:C3;
fixed-address 10.100.34.117;
}
# Host 3
host 3A684 {
filename "junk6.cm";
hardware ethernet 11:42:a3:13:a6:84;
fixed-address 10.100.34.119;
}
# Host 4
host 46d54 {
filename "junk4.cm";
hardware ethernet 23:10:3d:14:6d:54;
fixed-address 10.100.34.120;
}

[download]

In reply to Re: swapping lines that match a condition by jwkrahn
in thread swapping lines that match a condition by TheBigAmbulance

Title:
Use:  <p> text here (a paragraph) </p>
and:  <code> code here </code>
to format your post, it's "PerlMonks-approved HTML":


  • Posts are HTML formatted. Put <p> </p> tags around your paragraphs. Put <code> </code> tags around your code and data!
  • Titles consisting of a single word are discouraged, and in most cases are disallowed outright.
  • Read Where should I post X? if you're not absolutely sure you're posting in the right place.
  • Please read these before you post! —
  • Posts may use any of the Perl Monks Approved HTML tags:
    a, abbr, b, big, blockquote, br, caption, center, col, colgroup, dd, del, details, div, dl, dt, em, font, h1, h2, h3, h4, h5, h6, hr, i, ins, li, ol, p, pre, readmore, small, span, spoiler, strike, strong, sub, summary, sup, table, tbody, td, tfoot, th, thead, tr, tt, u, ul, wbr
  • You may need to use entities for some characters, as follows. (Exception: Within code tags, you can put the characters literally.)
            For:     Use:
    & &amp;
    < &lt;
    > &gt;
    [ &#91;
    ] &#93;
  • Link using PerlMonks shortcuts! What shortcuts can I use for linking?
  • See Writeup Formatting Tips and other pages linked from there for more info.