DOKK / manpages / debian 10 / tcl8.6-doc / concat.3tcl.en
concat(3tcl) Tcl Built-In Commands concat(3tcl) 







concat - Join lists together








concat ?arg arg ...?










This command joins each of its arguments together with spaces
    after trimming leading and trailing white-space from each of them. If all of
    the arguments are lists, this has the same effect as concatenating them into
    a single list. Arguments that are empty (after trimming) are ignored
    entirely. It permits any number of arguments; if no args are
    supplied, the result is an empty string.








Although concat will concatenate lists, flattening them in
    the process (so giving the following interactive session):






% concat a b {c d e} {f {g h}}
a b c d e f {g h}




it will also concatenate things that are not lists, as can be seen
    from this session:






% concat " a b {c   " d "  e} f"
a b {c d e} f




Note also that the concatenation does not remove spaces from the
    middle of values, as can be seen here:






% concat "a   b   c" { d e f }
a   b   c d e f




(i.e., there are three spaces between each of the a, the
    b and the c).








append(3tcl), eval(3tcl), join(3tcl)








concatenate, join, list







  

    8.3
    Tcl