SED Hints
Revision as of 13:47, 17 December 2015 by PeterHarding (talk | contribs) (Created page with " <pre> ------------------------------------------------------------------------------- Also see regex.hints for hints and tips of matching regular expressions And sed 1 lin...")
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Also see regex.hints for hints and tips of matching regular expressions
And sed 1 liners
http://sed.sourceforge.net/sed1line.txt
Also examples from the gnu "info sed"
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Print specific lines
print first line of file (emulates "head -1")
sed q
print first 10 lines of file (emulates behavior of "head")
sed 10q
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 '$!{h;d;}' -e x # for 1-line files, print nothing
print the last 2 lines of a file (emulates "tail -2")
sed '$!N;$!D'
print the last 10 lines of a file (emulates "tail")
sed -e :a -e '$q;N;11,$D;ba'
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Delete between Markers AAAA and BBBB
Inclusive delete (delete start and end)
sed '/AAAA/,/BBBB/d'
Exclusive delete (output start and end)
sed '1,/AAAA/p; /BBBB/,$p; d'
or
sed '/AAAA/,/BBBB/{ /AAAA/p; /BBBB/p; d }'
delete end but output start
sed '/AAAA/p; /AAAA/,/BBBB/d'
or
sed '/AAAA/,/BBBB/{ /AAAA/p; d }'
delete start but output end
sed '/AAAA/,/BBBB/{ /BBBB/p; d }'
or
sed '/BBBB/p; /AAAA/,/BBBB/d }'
See next...
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Print lines between markers AAAA to BBBB
Including markers
sed -n '/AAAA/,$p; /BBBB/q' file
Excluding the end marker
sed -n '/BBBB/q; /AAAA/,$p' file
or
sed -n '/AAAA/,$p; /BBBB/Q' file
Excluding both markers
sed -n '/BBBB/q; 1,/AAAA/d; p' file
or
sed '1,/AAAA/d; /BBBB/Q' file
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Line numbers
left aligned
sed = file | sed 'N;s/\n/\t/'
right aligned
sed = filename | sed 'N; s/^/ /; s/ *\(.\{6,\}\)\n/\1 /'
counting lines ("sed" only no "wc")
sed -n '$=' file
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Delete ALL blank lines
sed '/^$/d' file
Delete multiple blank lines (paragraph separators)
sed '/^$/{ N; /^\n$/D; }' file
or
sed '/./,/^$/!d' file
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Programming with sed....
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Delimiting "sed" Delimetors (also see next)
Say you want to search for a path name that contains slashes `/'
unfortunatally these are the sed regular expresion delimiters so you
need to escape the slashes before you can search for it. This is not as
easy as it sounds.
old_path="/some/path/to/look/for"
new_path="/some/path/to/look/for"
old_path=`echo "$old_path" | sed 's/\//\\\\\//g'`
new_path=`echo "$new_path" | sed 's/\//\\\\\//g'`
sed 's'"$old_path"'/'"$new_path"'/g' $old_file > $new_file
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Sed with arbatitry patterns
#!/bin/sh
# substitute {pattern} {replacement}
#
sed 's/'"$1"'/'"$2"'/g
That's OK provided you know for certain that $1 will never contain a "/"
or "\", and $2 will never contain a "/", "\" or "&". If $1 and $2 are
completely arbitrary you need to do something like:
pat=`echo "$1" | sed 's:[/\\]:\\&:g'`
rep=`echo "$2" | sed 's:[/\\&]:\\&:g'`
sed "s/$pat/$rep/g"
Is there a problem with """ or "`" in patterns? -- seems not
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Sed Programming Methology Example:
This sed script grabs a 'face' file (which always starts with a space or tab)
and repositions it correctly at the end of the mail header (denoted by a
absolutely blank line). NOTE the use of lables.
cat $FACE - $SIGNED | sed -n '
# first collect the new face at the start of the input
1 { s/^/X-Face:/; h; d; }
/^[ \t]/{H;d;}
# read the header; if X-face found just copy all
: head
/^X-Face:/ b body
/^$/ b face
p; n; b head
# output a face at end of header
:face
x; p; g; p; n
# just copy the rest of the file
: body
p; n; b body
' | /lib/sendmail "$@"
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Adding a newline to sed (just add return -- messy)
bourne shells:
sed 's/;$/; }\
/' filename
Csh family:
sed 's/;$/; }\\
/' filename
Of course you can always use a tr which is slower but neater
sed 's/;$/; }@/' | tr '@' '\012'
GNU sed allows you to use \r (for return)
But uses \n on the input side. Do not use \n on output as that is 'null'
sed 's/;$/; }\r/'
In a similar way it allows the use of \t for tab.
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Moving a line to the start of the file
EG
something1 this
something2 ====> something1
this something2
something3 something3
sed -n '
/this/!H # if no match append to hold space
/this/{x; H; } # found so exhange and append (prepend)
${g; s/\n//; p; }' <infile # if last line get and print hold
OR
sed '1,/this/{ # until found
/this/!{H; d; } # if not it put in hold (no print)
G; s-\n--; }' infile # otherwise output hold
# no match will continue print rest of file
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Word Division -- sed and non-sed version
Name=`echo $DISPLAY | sed 's/:.*//'`
can be done faster with
oldIFS=$IFS; IFS=.; set -- $DISPLAY; IFS=$oldIFS; Name=$1;
no fork, totally internal to shell
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Increment the number given
sed -e '
#Add zero to start if needed
/^9*$/ s/^/0/
# separate changing/unchanged digits with an x (and hold)
s/.9*$/x&/
h
# increment digits
s/^.*x//
y/0123456789/1234567890/
# merge unchanged with changed
x
s/x.*$//
G
s/\n//
'
Alturnative without using the hold buffer
sed -e '
/[^0-9]/ d
# replace all leading 9s by _ (any non-digit could be used)
:d
s/9\(_*\)$/_\1/
td
# incr last digit only. The first line adds a most-significant
# digit of 1 if we have to add a digit.
#
# The t commands are not necessary, but make the thing faster
s/^\(_*\)$/1\1/; tn
s/8\(_*\)$/9\1/; tn
s/7\(_*\)$/8\1/; tn
s/6\(_*\)$/7\1/; tn
s/5\(_*\)$/6\1/; tn
s/4\(_*\)$/5\1/; tn
s/3\(_*\)$/4\1/; tn
s/2\(_*\)$/3\1/; tn
s/1\(_*\)$/2\1/; tn
s/0\(_*\)$/1\1/; tn
:n
y/_/0/
'
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Count 'a's on a line
sed -e '
# convert groups of ten to a higher order
# The t and b are not necessary, but is faster
t a
: a; s/aaaaaaaaaa/b/g; t b; b done
: b; s/bbbbbbbbbb/c/g; t c; b done
: c; s/cccccccccc/d/g; t d; b done
: d; s/dddddddddd/e/g; t e; b done
: e; s/eeeeeeeeee/f/g; t f; b done
: f; s/ffffffffff/g/g; t g; b done
: g; s/gggggggggg/h/g; t h; b done
: h; s/hhhhhhhhhh//g
: done
# convert back to numbers
: loop
/a/! s/[b-h]*/&0/
s/aaaaaaaaa/9/
s/aaaaaaaa/8/
s/aaaaaaa/7/
s/aaaaaa/6/
s/aaaaa/5/
s/aaaa/4/
s/aaa/3/
s/aa/2/
s/a/1/
# loop to do next digit
y/bcdefgh/abcdefg/
/[a-h]/ b loop
'
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Reverse characters in a line
sed -e '
# skip lines with lest than two characters
/../! b
# Embed newlines at both ends
# then slowly meove markers toward middle
:x
s/\(\n.\)\(.*\)\(.\n\)/\3\2\1/
tx
# remove newline markers
s/\n//g
'
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