Shell Programming and Scripting

awk -F, '{if ($NF ~ /^[0-9]|^[A-Za-z]/) print >"goodfile";else print >"badfile"}' filename

1,abc,def,1234,A *
2,bed,dec,342,* A         
3,dec,345,23,*&^          
4,sdf,fgh,234,  
5,ert,345,ghj,C**
6,ert,345,sdf,123          ---- only valid record

2,bed,dec,342,* A 
3,dec,345,23,*&^ 
4,sdf,fgh,234,

awk ' /[0-9]$|[A-Za-z]$/{print >"goodfile";next}{print >"badfile"}' infile

awk -F, '{if ($NF ~ /[0-9]$|[A-Za-z]$/) print >"goodfile"; else print >"badfile"}' samp.txt

1,abc,def,1234,A *
2,bed,dec,342,* A
3,dec,345,23,*&^
4,sdf,fgh,234,
5,ert,345,ghj,C*2
6,ert,345,sdf,123

$ cat goodfile
2,bed,dec,342,* A
5,ert,345,ghj,C*2
6,ert,345,sdf,123
$ cat badfile
1,abc,def,1234,A *
3,dec,345,23,*&^
4,sdf,fgh,234,

awk -F, '{if ($NF ~ /[0-9]$|[A-Za-z]$/) {print >"goodfile"} else {print >"badfile" }}'  infile

$ cat samp.txt
1,abc,def,1234,A *
2,bed,dec,342,* A
3,dec,345,23,*&^
4,sdf,fgh,234,
5,ert,345,ghj,C*2
6,ert,345,sdf,123

$ awk -F, '{if ($NF ~ /[0-9]$|[A-Za-z]$/) {print >"goodfile"} else {print >"badfile" }}' samp.txt

$ cat goodfile
2,bed,dec,342,* A
5,ert,345,ghj,C*2
6,ert,345,sdf,123

$ cat badfile
1,abc,def,1234,A *
3,dec,345,23,*&^
4,sdf,fgh,234,

awk -F, '{if ($NF~/[0-9A-Za-z][0-9A-Za-z][0-9A-Za-z]/) print >"goodfile"; else print>"badfile}' samp.txt

awk -F, '{if($NF~/^[[:alnum:][:blank:]]+$/) print > "goodfile"; else print > "badfile"}' infile