Shell Programming and Scripting

FILE_001.txt
FILE_002.txt
FILE_005.txt
FILE_006.txt
FILE_008.txt
FILE_009.txt
FILE_010.txt
FILE_014.txt

FILE_003.txt
FILE_004.txt
FILE_007.txt
FILE_011.txt
FILE_012.txt
FILE_013.txt

003
004
007
011
012
013

#!/bin/ksh

#Do a file listing and count and set variables

ls FILE* > answers.txt
tot_line=`wc -l answers.txt | awk '{print $1}'`
typeset -Z3 file_missing
current_line=1
next_line=2

#loop through list of files getting the file number

while [ $current_line -lt $tot_line ]
do
current_file=`awk 'NR=='$current_line'' answers.txt | sed 's/\(.*_\)\(.*[0-9]\)\
(.*$\)/\2/'`
next_file=`awk 'NR=='$next_line'' answers.txt | sed 's/\(.*_\)\(.*[0-9]\)\(.*$\)
/\2/'`

#find out if files are sequential

sequence=`expr $next_file - $current_file`

#If files not sequential start loop to print list of unsequential files

if [ $sequence -ne 1 ]
then
curr_file=$current_file
while [ $sequence -gt 1 ]
do

file_missing=`expr $curr_file + 1`
curr_file=`expr $curr_file + 1`

echo "FILE_$file_missing.txt is missing"
sequence=`expr $sequence - 1`
done

fi

current_line=`expr $current_line + 1`
next_line=`expr $next_line + 1`

done

for i in {1..14}
do
seq=`printf "%03d" $i`
if [ ! -f "FILE_${seq}.txt" ]
then
echo "FILE_${i}.txt"
fi
done

#!/bin/ksh
first=1
missing=0

nextfile() {
	seq=$((seq + 1))
	next=$(printf 'FILE_%03d.txt' "$seq")
}

for i in FILE_[0-9][0-9][0-9].txt
do	if [ "$first" = 1 ]
	then	if [ ! -f "$i" ]
		then	printf 'No files matching pattern found.\n' >&2
			exit 1
		fi
		seq=${i#FILE_}
		seq=${seq#0}	# Avoid problems with some shells treating
		seq=${seq#0}	# numbers with leading zeros as octal.
		seq=${seq%.txt}
		first=
		continue
	fi
	nextfile
	while [ "$next" != "$i" ]
	do	printf '%s is missing\n' "$next"
		missing=$((missing + 1))
		nextfile
	done
done
if [ "$missing" = 0 ]
then	printf 'No missing files detected.\n'
fi

ls | awk '
function xmatch() {
  if ( match($0,/[0-9]+/) ) {
    x=substr($0,RSTART,RLENGTH)+0
  } else {
    print ">>"$0
    x=0
  }
}
n {
  xmatch(); if (x) {
    for ( ; ++n<x; ) { printf "%0*d\n", RLENGTH, n }
  }
  next
}
{
  xmatch(); n=x
}
'