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Top Forums Shell Programming and Scripting sed search pattern and delete lines Post 302701795 by Don Cragun on Monday 17th of September 2012 10:42:08 AM
Old 09-17-2012
Eightball,
You said you want to delete two lines before the matched line and one line after the matched line, but your example deletes two lines before the match line and the matched line (leaving the line after the match as it was).

The script Ygor provided will provide output matching your example output, but only works on Linux systems (according to the man pages provided on this site, the tac utility is not available on OpenSolaris, FreeBSD, OSX, or POSIX systems).

The following ed script should work on any of these systems:
Code:
#!/bin/ksh
# Usage: edscript pattern input_file output_file
#    Find the 1st line in "input_file" selected by the basic regular
#    expression "BRE"; delet the selected line, two lines before it, and
#    one line after it; and write the update file to "output_file".
ed -s "$2" <<-END
        /$1/-2;.+2d
        w $3
END

save the above script in a file named edscript, make it executable by running the command:
Code:
chmod +x edscript

and then (assuming the input file you specified in your example is named in, execute the command:
Code:
edscript MICHAEL in out

to make the changes suggested by the sample output you provided and save the output in a file named out.
 

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TEST(1) 						      General Commands Manual							   TEST(1)

NAME
test - condition command SYNOPSIS
test expr DESCRIPTION
test evaluates the expression expr, and if its value is true then returns zero exit status; otherwise, a non zero exit status is returned. test returns a non zero exit if there are no arguments. The following primitives are used to construct expr. -r file true if the file exists and is readable. -w file true if the file exists and is writable. -f file true if the file exists and is not a directory. -d file true if the file exists and is a directory. -s file true if the file exists and has a size greater than zero. -t [ fildes ] true if the open file whose file descriptor number is fildes (1 by default) is associated with a terminal device. -z s1 true if the length of string s1 is zero. -n s1 true if the length of the string s1 is nonzero. s1 = s2 true if the strings s1 and s2 are equal. s1 != s2 true if the strings s1 and s2 are not equal. s1 true if s1 is not the null string. n1 -eq n2 true if the integers n1 and n2 are algebraically equal. Any of the comparisons -ne, -gt, -ge, -lt, or -le may be used in place of -eq. These primaries may be combined with the following operators: ! unary negation operator -a binary and operator -o binary or operator ( expr ) parentheses for grouping. -a has higher precedence than -o. Notice that all the operators and flags are separate arguments to test. Notice also that parentheses are meaningful to the Shell and must be escaped. SEE ALSO
sh(1), find(1) TEST(1)
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