-toutputs what it's going to perform before performing it-Ireplaces occurrences of the argument with whatever is piped into it
cat file.txt | xargs sh -c "<command>; <commandtwo>"cat file.txt | xargs -I "{}" sh -c "cd {}; <command_in_dir>"-t outputs what it's going to perform before performing it-I replaces occurrences of the argument with whatever is piped into itcat file.txt | xargs sh -c "<command>; <commandtwo>"cat file.txt | xargs -I "{}" sh -c "cd {}; <command_in_dir>"