linux sed III

print first 10 lines of file (emulates behavior of "head") double space a file

 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 only lines which match regular expression (emulates "grep")

 sed -n '/regexp/p'           # method 1
 sed '/regexp/!d'             # method 2

print only lines which do NOT match regexp (emulates "grep -v")

 sed -n '/regexp/!p'          # method 1, corresponds to above
 sed '/regexp/d'              # method 2, simpler syntax

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 and BBB and CCC (in any order)

 sed '/AAA/!d; /BBB/!d; /CCC/!d'

grep for AAA and BBB and CCC (in that order)

 sed '/AAA.*BBB.*CCC/!d'

grep for AAA or BBB or CCC (emulates "egrep")

 sed -e '/AAA/b' -e '/BBB/b' -e '/CCC/b' -e d    # most seds
 gsed '/AAA\|BBB\|CCC/!d'                        # GNU sed only

print paragraph if it contains AAA (blank lines separate paragraphs) HHsed v1.5 must insert a 'G;' after 'x;' in the next 3 scripts below

 sed -e '/./{H;$!d;}' -e 'x;/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

 gsed -n '3~7p'               # GNU sed only
 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

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 first 10 lines of a file

 sed '1,10d'

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

 gsed '0~8d'                           # GNU sed only
 sed 'n;n;n;n;n;n;n;d;'                # other seds

delete lines matching pattern

 sed '/pattern/d'

delete ALL blank lines from a file (same as "grep '.' ")

 sed '/^$/d'                           # method 1
 sed '/./!d'                           # method 2

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
 sed -e :a -e '/^\n*$/N;/\n$/ba'        # ditto, except for gsed 3.02.*

delete the last line of each paragraph

 sed -n '/^$/{p;h;};/./{x;/./p;}'