string-join - join strings with delimiter — fish-shell 4.8.0 documentation

# string-join - join strings with delimiter

## Synopsis

    string join [-q | --quiet] [-n | --no-empty] [--] SEP [STRING ...]
    string join0 [-q | --quiet] [-n | --no-empty] [--] [STRING ...]

## Description

Joins its STRING arguments into a single string separated by SEP (for `string join`) or by the zero byte (NUL) (for `string join0`). Exit status: 0 if at least one join was performed, or 1 otherwise.

-n, --no-empty

  Exclude empty strings from consideration (e.g. `string join -n + a b "" c` would expand to `a+b+c` not `a+b++c`).

-q, --quiet

  Do not print the strings, only set the exit status as described above.

WARNING: Insert a `--` before positional arguments to prevent them from being interpreted as flags. Otherwise, any strings starting with `-` will be treated as flag arguments, meaning they will most likely result in the command failing. This is also true if you specify a variable which expands to such a string instead of a literal string. If you don’t need to append flag arguments at the end of the command, just always use `--` to avoid unwelcome surprises.

`string join0` adds a trailing NUL. This is most useful in conjunction with tools that accept NUL-delimited input, such as `sort -z`.

Because Unix uses NUL as the string terminator, passing the output of `string join0` as an argument to a command (via a command substitution) won’t actually work. fish will pass the correct bytes along, but the command won’t be able to tell where the argument ends. This is a limitation of Unix’ argument passing.

## Examples

    >_ seq 3 | string join ...
    1...2...3

    # Give a list of NUL-separated filenames to du (this is a GNU extension)
    >_ string join0 file1 file2 file\nwith\nmultiple\nlines | du --files0-from=-

    # Just put the strings together without a separator
    >_ string join '' a b c
    abc

    >_ set -l markdown_list '- first' '- second' '- third'
    # Strings with leading hyphens (also in variable expansions) are interpreted as flag arguments by default.
    >_ string join \n $markdown_list
    string join: - first: unknown option
    # Use '--' to prevent this.
    >_ string join -- \n $markdown_list
    - first
    - second
    - third