Shell Programming and Scripting

#!/usr/bin/env bash

# @(#) s1       Demonstrate delete all previous line before last matching line, awk, gawk.

PATTERN=${1-"Line 1"}

# Utility functions: print-as-echo, print-line-with-visual-space, debug.
# export PATH="/usr/local/bin:/usr/bin:/bin"
LC_ALL=C ; LANG=C ; export LC_ALL LANG
pe() { for _i;do printf "%s" "$_i";done; printf "\n"; }
pl() { pe;pe "-----" ;pe "$*"; }
em() { pe "$*" >&2 ; }
db() { ( printf " db, ";for _i;do printf "%s" "$_i";done;printf "\n" ) >&2 ; }
db() { : ; }
C=$HOME/bin/context && [ -f $C ] && $C awk

pl " Pattern: \"$PATTERN\""

FILE=data1
N=${FILE//[A-Za-z]/}
E=expected-output$N

pl " Input data file $FILE:"
cat $FILE

pl " Expected output:"
cat $E

pl " Results:"
awk -vPATTERN="$PATTERN" '
BEGIN   { i = 0 }
$0 ~ PATTERN    { i =  0; next }
                { i++ ; a[i] = $0 } 
END     { size = length(a) ; for (i=1;i<=size;i++) { print a[i] } }
' $FILE |
tee f1

pl " Verify results if possible:"
C=$HOME/bin/pass-fail
[ -f $C ] && $C f1 $E || ( pe; pe " Results cannot be verified." ) >&2

exit 0

$ ./s1

Environment: LC_ALL = C, LANG = C
(Versions displayed with local utility "version")
OS, ker|rel, machine: Linux, 3.16.0-4-amd64, x86_64
Distribution        : Debian 8.9 (jessie) 
bash GNU bash 4.3.30
awk GNU Awk 4.1.1, API: 1.1 (GNU MPFR 3.1.2-p3, GNU MP 6.0.0)

-----
 Pattern: "Line 1"

-----
 Input data file data1:
Line 1 a
Line 22
Line 33
Line 1 b
Line 22
Line 1 c
Line 4
Line 5

-----
 Expected output:
Line 4
Line 5

-----
 Results:
Line 4
Line 5

-----
 Verify results if possible:

-----
 Comparison of 2 created lines with 2 lines of desired results:
 Succeeded -- files (computed) f1 and (standard) expected-output1 have same content.

OS, ker|rel, machine: SunOS, 5.11, i86pc
Distribution        : Solaris 11.3 X86
gawk GNU Awk 3.1.8

var="Line 1"
exec 3>outfile
while read line
do
  case $line in
  *$var*) exec 3>outfile
  ;;
  *)echo "$line" >&3
  ;; 
  esac
done <inputfile