PeterHarding at 02:48, 17 December 2015

2015-12-17T02:48:22Z

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	-------------------------------------------------------------------------------		-------------------------------------------------------------------------------
	Also see regex.hints for hints and tips of matching regular expressions		Also see regex.hints for hints and tips of matching regular expressions

PeterHarding at 02:48, 17 December 2015

2015-12-17T02:48:09Z

← Older revision		Revision as of 12:48, 17 December 2015
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			From - https://www.ict.griffith.edu.au/anthony/info/shell/sed.hints

	<pre>		<pre>

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  ------------------------------------------------------------------------------- Also see  regex.hints  for hints and tips of matching regular expressions And sed 1 lin..."

2015-12-17T02:47:33Z

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<pre>

-------------------------------------------------------------------------------
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"

------------------------------------------------------------------------------
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'

------------------------------------------------------------------------------
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...

------------------------------------------------------------------------------
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

-------------------------------------------------------------------------------
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

------------------------------------------------------------------------------
Delete ALL blank lines
sed '/^$/d' file

Delete multiple blank lines (paragraph separators)
sed '/^$/{ N; /^\n$/D; }' file
or
sed '/./,/^$/!d' file

===============================================================================
Programming with sed....

------------------------------------------------------------------------------
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

-------------------------------------------------------------------------------
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

-------------------------------------------------------------------------------
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 "$@"

-------------------------------------------------------------------------------
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.

-------------------------------------------------------------------------------
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

-------------------------------------------------------------------------------
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

------------------------------------------------------------------------------
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/
'

-------------------------------------------------------------------------------
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
'

------------------------------------------------------------------------------
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
'

-------------------------------------------------------------------------------
</pre>

[[Category:Sed]]
[[Category:UNIX Tools]]

SED Hints - Revision history

PeterHarding at 02:48, 17 December 2015

PeterHarding at 02:48, 17 December 2015

PeterHarding: Created page with "
------------------------------------------------------------------------------- Also see regex.hints for hints and tips of matching regular expressions And sed 1 lin..."