Joining 2 files on the first field

Question

I would like to compare the two files file1 $1 is equal to file2 $1 and display the output file1 $1,$2,$3,$4,$5, file2 $2,$5. and difference of file1 $5 - file2 $5

input file 1.txt

1,raja,AP,NIND,14:51:56.46
2,mona,KR,SIND,12:41:46.36
3,JO,TM,SIND,18:31:56.36
4,andrew,sind,13:43:23.12
5,drew,sind,17:53:53.42

input file 2.txt

5,raju,UP,NIND,11:51:56.46
6,NAG,KR,SIND,12:41:46.36
7,JO,TM,SIND,18:31:56.36
8,andrew,sind,kkd,14:43:23.12
4,andrew,sind,ggf,15:53:53.42
10,asJO,TM,SIND,16:31:56.36
3,sandrew,sind,gba,9:43:23.12
2,xcandrew,sind,sds,6:53:53.42
1,cv,GTM,SIND,5:31:56.36
9,mnJO,TM,SIND,2:20:56.36

output:

1,raja,AP,NIND,14:51:56.46,cv,5:31:56.36 
2,mona,KR,SIND,12:41:46.36,xcandrew,6:53:53.42
3,JO,TM,SIND,18:31:56.36,sandrew,9:43:23.12
4,andrew,sind,13:43:23.12,andrew,15:53:53.42
5,drew,sind,17:53:53.42,raju,11:51:56.46

Answer 1

With awk you would do:

$ awk 'NR==FNR{a[$1]=$0;next}$1 in a{print a[$1],$2,$5}' FS=, OFS=, f1 f2
5,drew,sind,17:53:53.42,raju,11:51:56.46
4,andrew,sind,13:43:23.12,andrew,
3,JO,TM,SIND,18:31:56.36,sandrew,
2,mona,KR,SIND,12:41:46.36,xcandrew,
1,raja,AP,NIND,14:51:56.46,cv,5:31:56.36

If you want the output sorted then pipe to sort:

$ awk 'NR==FNR{a[$1]=$0;next}$1 in a{print a[$1],$2,$5}' FS=, OFS=, f1 f2 | sort
1,raja,AP,NIND,14:51:56.46,cv,5:31:56.36
2,mona,KR,SIND,12:41:46.36,xcandrew,
3,JO,TM,SIND,18:31:56.36,sandrew,
4,andrew,sind,13:43:23.12,andrew,
5,drew,sind,17:53:53.42,raju,11:51:56.46

Alternative using join:

$ join -j1 -t, -o 1.1,1.2,1.3,1.4,1.5,2.2,2.5 <(sort f1) <(sort f2)
1,raja,AP,NIND,14:51:56.46,cv,5:31:56.36
2,mona,KR,SIND,12:41:46.36,xcandrew,
3,JO,TM,SIND,18:31:56.36,sandrew,
4,andrew,sind,13:43:23.12,,andrew,
5,drew,sind,17:53:53.42,,raju,11:51:56.46