Shell Programming and Scripting

Hello, I'm having trouble to read two txt files, they have employee records line by line, I need to do the reading of a file that is old and compare it with the new base in the new file, deleting the lines in old file, then add the new file data from the old file and write to the database manager.

I am new to Shell, I appreciate the help

Please show a sample of the two files and the desired output.

Old File
374905,2008, Selmar Evangelista dos Santos Filho, Analista de Sistemas, U$5.500,00
751890,2005, Ricardo de Souza, Técnico de sistemas, U$8.000,00
986250,2000, Eric Bastos, Gerente, U$10.000,00
...

New File
986250,2000, Eric Bastos, Gerente, U$12.000,00
859762, 2009, Fabiana Castro Neves, Assistente Administrativa, U$2.000,00
374905,2008, Selmar Evangelista dos Santos Filho, Analista de Sistemas, U$9.500,00
...

Result = New File
986250,2000, Eric Bastos, Gerente, U$12.000,00
859762, 2009, Fabiana Castro Neves, Assistente Administrativa, U$2.000,00
374905,2008, Selmar Evangelista dos Santos Filho, Analista de Sistemas, U$9.500,00
751890,2005, Ricardo de Souza, Técnico de sistemas, U$8.000,00

Thanks for all.

How about:

Code:

[house@leonov] cat old.file new.file | sort -k 1,1 -u -r
986250,2000, Eric Bastos, Gerente, U$10.000,00
859762, 2009, Fabiana Castro Neves, Assistente Administrativa, U$2.000,00
751890,2005, Ricardo de Souza, Técnico de sistemas, U$8.000,00
374905,2008, Selmar Evangelista dos Santos Filho, Analista de Sistemas, U$5.500,00

Something like this:

Code:

awk -F"," 'NR==FNR { a[$1","$2]=$1","$2;print;next} {if($1","$2 in a) next;else print; }' new_file old_file