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