---
name: "concat"
section: "3tcl"
platform: "linux"
package: "tcl8.6-doc"
version: "8.6.16+dfsg-1"
release: "Debian 13 (Trixie)"
platforms: ["linux"]
url: "https://new.carta.tech/concat"
---

# concat(3tcl)

Join lists together

```

```

## NAME

concat - Join lists together

## SYNOPSIS

**concat** ?*arg arg ...*?

```

```

## DESCRIPTION

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 *arg*s are supplied, the result is an empty string.

## EXAMPLES

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**).

## SEE ALSO

[append(3tcl)](/append/3tcl.md), [eval(3tcl)](/eval/3tcl.md), [join(3tcl)](/join/3tcl.md)

## KEYWORDS

concatenate, join, list