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 | program1While 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 < abcor, if program1 supports it
program1 abc