【知识涌升】sed高级篇《sed单行脚本》

这才是真的大师之作 原文地址http://sed.sourceforge.net/sed1line.txt

FILE SPACING:

 # double space a file
 sed G

 # double space a file which already has blank lines in it. Output file
 # should contain no more than one blank line between lines of text.
 sed '/^$/d;G'

 # triple space a file
 sed 'G;G'

 # undo double-spacing (assumes even-numbered lines are always blank)
 sed 'n;d'

 # insert a blank line above every line which matches "regex"
 sed '/regex/{x;p;x;}'

 # insert a blank line below every line which matches "regex"
 sed '/regex/G'

 # insert a blank line above and below every line which matches "regex"
 sed '/regex/{x;p;x;G;}'

NUMBERING:

 # number each line of a file (simple left alignment). Using a tab (see
 # note on '\t' at end of file) instead of space will preserve margins.
 sed = filename | sed 'N;s/\n/\t/'

 # number each line of a file (number on left, right-aligned)
???????? sed = filename | sed 'N; s/^/     /; s/ *\(.\{6,\}\)\n/\1  /'

 # number each line of file, but only print numbers if line is not blank
 sed '/./=' filename | sed '/./N; s/\n/ /'

 # count lines (emulates "wc -l")
 sed -n '$='

TEXT CONVERSION AND SUBSTITUTION:

 # align all text flush right on a 79-column width
 sed -e :a -e 's/^.\{1,78\}$/ &/;ta'  # set at 78 plus 1 space

 # center all text in the middle of 79-column width. In method 1,
 # spaces at the beginning of the line are significant, and trailing
 # spaces are appended at the end of the line. In method 2, spaces at
 # the beginning of the line are discarded in centering the line, and
 # no trailing spaces appear at the end of lines.
 sed  -e :a -e 's/^.\{1,77\}$/ & /;ta'                     # method 1
 sed  -e :a -e 's/^.\{1,77\}$/ &/;ta' -e 's/\( *\)\1/\1/'  # method 2

 # substitute (find and replace) "foo" with "bar" on each line
 sed 's/foo/bar/'             # replaces only 1st instance in a line
 sed 's/foo/bar/4'            # replaces only 4th instance in a line
 sed 's/foo/bar/g'            # replaces ALL instances in a line
 sed 's/\(.*\)foo\(.*foo\)/\1bar\2/' # replace the next-to-last case
 sed 's/\(.*\)foo/\1bar/'            # replace only the last case

# reverse order of lines (emulates "tac")
 # bug/feature in HHsed v1.5 causes blank lines to be deleted
 sed '1!G;h;$!d'               # method 1
 sed -n '1!G;h;$p'             # method 2

 # reverse each character on the line (emulates "rev")
 sed '/\n/!G;s/\(.\)\(.*\n\)/&\2\1/;//D;s/.//'

 # join pairs of lines side-by-side (like "paste")
 sed '$!N;s/\n/ /'

 # if a line ends with a backslash, append the next line to it
 sed -e :a -e '/\\$/N; s/\\\n//; ta'

 # if a line begins with an equal sign, append it to the previous line
 # and replace the "=" with a single space
 sed -e :a -e '$!N;s/\n=/ /;ta' -e 'P;D'

 # add commas to numeric strings, changing "1234567" to "1,234,567"
 sed -e :a -e 's/\(.*[0-9]\)\([0-9]\{3\}\)/\1,\2/;ta'  # other seds

 # add a blank line every 5 lines (after lines 5, 10, 15, 20, etc.)
 sed 'n;n;n;n;G;'             # other seds

SELECTIVE PRINTING OF CERTAIN LINES:

 # print first 10 lines of file (emulates behavior of "head")
 sed 10q

 # print first line of file (emulates "head -1")
 sed q

 # print the last 10 lines of a file (emulates "tail")
 sed -e :a -e '$q;N;11,$D;ba'

 # print the last 2 lines of a file (emulates "tail -2")
 sed '$!N;$!D'

 # print the last line of a file (emulates "tail -1")
 sed '$!d'                    # method 1
 sed -n '$p'                  # method 2

 # print the next-to-the-last line of a file
 sed -e '$!{h;d;}' -e x              # for 1-line files, print blank line
 sed -e '1{$q;}' -e '$!{h;d;}' -e x  # for 1-line files, print the line
 sed -e '1{$d;}' -e '$!{h;d;}' -e x  # for 1-line files, print nothing

 # print the line immediately before a regexp, but not the line
 # containing the regexp
 sed -n '/regexp/{g;1!p;};h'

 # print the line immediately after a regexp, but not the line
 # containing the regexp
 sed -n '/regexp/{n;p;}'

 # print 1 line of context before and after regexp, with line number
 # indicating where the regexp occurred (similar to "grep -A1 -B1")
 sed -n -e '/regexp/{=;x;1!p;g;$!N;p;D;}' -e h

 # grep for AAA or BBB or CCC (emulates "egrep")
 sed -e '/AAA/b' -e '/BBB/b' -e '/CCC/b' -e d    # most seds

 # print paragraph if it contains AAA (blank lines separate paragraphs)
 sed -e '/./{H;$!d;}' -e 'x;G;/AAA/!d;'

 # print paragraph if it contains AAA and BBB and CCC (in any order)
 sed -e '/./{H;$!d;}' -e 'x;/AAA/!d;/BBB/!d;/CCC/!d'

 # print paragraph if it contains AAA or BBB or CCC
 sed -e '/./{H;$!d;}' -e 'x;/AAA/b' -e '/BBB/b' -e '/CCC/b' -e d
 gsed '/./{H;$!d;};x;/AAA\|BBB\|CCC/b;d'         # GNU sed only

 # print only lines of 65 characters or longer
 sed -n '/^.\{65\}/p'

 # print only lines of less than 65 characters
 sed -n '/^.\{65\}/!p'        # method 1, corresponds to above
 sed '/^.\{65\}/d'            # method 2, simpler syntax

 # print section of file from regular expression to end of file
 sed -n '/regexp/,$p'

 # print section of file based on line numbers (lines 8-12, inclusive)
 sed -n '8,12p'               # method 1
 sed '8,12!d'                 # method 2

 # print line number 52
 sed -n '52p'                 # method 1
 sed '52!d'                   # method 2
 sed '52q;d'                  # method 3, efficient on large files

 # beginning at line 3, print every 7th line
 sed -n '3,${p;n;n;n;n;n;n;}' # other seds

 # print section of file between two regular expressions (inclusive)
 sed -n '/Iowa/,/Montana/p'             # case sensitive

SELECTIVE DELETION OF CERTAIN LINES:

 # print all of file EXCEPT section between 2 regular expressions
 sed '/Iowa/,/Montana/d'

 # delete duplicate, consecutive lines from a file (emulates "uniq").
 # First line in a set of duplicate lines is kept, rest are deleted.
 sed '$!N; /^\(.*\)\n\1$/!P; D'

 # delete duplicate, nonconsecutive lines from a file. Beware not to
 # overflow the buffer size of the hold space, or else use GNU sed.
 sed -n 'G; s/\n/&&/; /^\([ -~]*\n\).*\n\1/d; s/\n//; h; P'

 # delete all lines except duplicate lines (emulates "uniq -d").
 sed '$!N; s/^\(.*\)\n\1$/\1/; t; D'

 # delete the last line of a file
 sed '$d'

 # delete the last 2 lines of a file
 sed 'N;$!P;$!D;$d'

 # delete the last 10 lines of a file
 sed -e :a -e '$d;N;2,10ba' -e 'P;D'   # method 1
 sed -n -e :a -e '1,10!{P;N;D;};N;ba'  # method 2

 # delete every 8th line
 sed 'n;n;n;n;n;n;n;d;'                # other seds

 # delete all CONSECUTIVE blank lines from file except the first; also
 # deletes all blank lines from top and end of file (emulates "cat -s")
 sed '/./,/^$/!d'          # method 1, allows 0 blanks at top, 1 at EOF
 sed '/^$/N;/\n$/D'        # method 2, allows 1 blank at top, 0 at EOF

 # delete all CONSECUTIVE blank lines from file except the first 2:
???????? sed '/^$/N;/\n$/N;//D'

 # delete all leading blank lines at top of file
 sed '/./,$!d'

 # delete all trailing blank lines at end of file
 sed -e :a -e '/^\n*$/{$d;N;ba' -e '}'  # works on all seds

 # delete the last line of each paragraph
 sed -n '/^$/{p;h;};/./{x;/./p;}'

黑色字体的是一般借鉴意义的例子，粉色是非常有借鉴价值的例子，红色是至今还有迷糊的例子。

感觉有点要明白了的感觉，sed的大牛真的很多，尤其是在国外的几个网站上，蹲了一大堆特别牛的人，尤其是见识了sed还可以干这干那的。

通过读这个单行脚本，理解了pattern space/hold space和d，D这俩控制执行顺序的命令，以前知道的都太浅了~~~