Reference Manual

cat - concatenate files and write to standard output
catb - concatenate binary files

cat file...

Command cat concatenates a set of files by opening them one at a time and writing their contents to standard output. Because standard output normally goes to the window in which the shell runs, invoking cat on a single file causes the contents of the file to be written to that window.

Command catb performs the same operations as cat but reads files in binary mode.

echo