Shell Programming and Scripting

2,"URL","website","aaa.com"
2,"abc","text","some text"
2,"Password","password","12345678"
3,"URL","website","10.0.10.75"
3,"uname","text","some text"
3,"Password","password","password"
3,"ulang","text","some text"
4,"URL","website","192.168.2.110"
4,"Login","login","admin"
4,"Password","password","blah-blah"

2,"URL","website","aaa.com","abc","text","some text",Password","password","12345678"
3,"URL","website","10.0.10.75","uname","text","some text""Password","password","password","ulang","text","some text"

awk -F, 'NR!=1 && p1!=$1{print prev;prev=""}
{p1=$1;prev=(prev"")?prev FS substr($0,index($0,$2)):$0}
END{if(prev"") print prev}' file

awk -F "," 's != $1 || NR ==1{s=$1;if(p){print p};p=$0;next}
{sub($1,"",$0);p=p""$0;}END{print p}' file

# While NR (number of records) is not equal to 1 and p1 is not equal to the first field (the ID)
NR!=1 && p1!=$1

# Print the line and append a null so the line will join with the next
{print prev;prev=""}

# p1 gets the value of the ID field
{p1=$1;

# This is a bit cryptic, but it looks like you're assigning/merging the contents
# of previous line with the next one and stripping the first field??
prev=(prev"")?prev FS substr($0,index($0,$2)):$0}

# Also a bit cryptic, but guessing we've reached the EOF and spitting out what's left?
END{if(prev"") print prev}'

prev=(prev"")?prev FS substr($0,index($0,$2)):$0