Felis domestica, a small animal that usually lives in house provided by its staff.

Felis Felis sylvestris catus, from an alternate (and detailed) phylogeny (at least you can see why cat). See for more...

cat, a small utility that usually lives in bin provided by root's staff. PBO The name is said to be an abbrev. of concatenate, which is one of cat's uses.

Here's a partial reimplementation in Tcl from Playing Bourne shell (it does not write to stdout, but returns its results, for the caller to process further):

 proc cat files {
    set res ""
    foreach file [eval glob $files] {
        set fp [open $file]
        append res [read $fp [file size $file]]
        close $fp
    set res
 } ;# RS

See computer-assisted translation

LV Too often, I see script writers misuse cat. For instance, they might write:

 cat abc | program1

While there are certainly times when cat-ing into a pipeline is the right things to do, this particular, simple, use is typically better written as

  program1 < abc

or, if program1 supports it

 program1 abc