JOSE-FMT(1)   JOSE-FMT(1)

jose-fmt - Converts JSON between serialization formats

jose fmt [OPTIONS]

This jose fmt command provides a mechanism for building and parsing JSON objects from the command line. It operates as a simple stack machine. All commands operate on the TOP item of the stack and, occasionally, the PREV item of the stack. Commands that require a specific type of value will indicate it in parentheses. For example: "TOP (arr.)".

This program returns 0 on success or the index of the option which failed.

•-0, --null : Assert TOP to be null
•-a, --append : Append TOP to the end of PREV (arr.)
•-a, --append : Set missing values from TOP (obj.) into PREV (obj.)
•-A, --array : Assert TOP to be an array
•-B, --boolean : Assert TOP to be a boolean
•-c, --copy : Deep copy TOP, push onto TOP
•-d NAME, --delete=NAME : Delete NAME from TOP (obj.)
•-d , --delete= : Delete # from TOP (arr.)
•-d -, --delete=- : Delete # from the end of TOP (arr.)
•-e, --empty : Erase all items from TOP (arr./obj.)
•-E, --equal : Assert TOP to be equal to PREV
•-f FILE, --foreach=FILE : Write TOP (obj./arr.) to FILE, one line/item
•-f -, --foreach=- : Write TOP (obj./arr.) to STDOUT, one line/item
•-F, --false : Assert TOP to be false
•-g NAME, --get=NAME : Get item with NAME from TOP (obj.), push to TOP
•-g , --get= : Get # item from TOP (arr.), push to TOP
•-g -, --get=- : Get # item from the end of TOP (arr.), push to TOP
•-i , --insert= : Insert TOP into PREV (arr.) at #
•-I, --integer : Assert TOP to be an integer
•-j JSON, --json=JSON : Parse JSON constant, push onto TOP
•-j FILE, --json=FILE : Read from FILE, push onto TOP
•-j -, --json=- : Read from STDIN, push onto TOP
•-l, --length : Push length of TOP (arr./str./obj.) to TOP
•-M , --move= : Move TOP back # places on the stack
•-N, --number : Assert TOP to be a number
•-o FILE, --output=FILE : Write TOP to FILE
•-o -, --output=- : Write TOP to STDOUT
•-O, --object : Assert TOP to be an object
•-q STR, --quote=STR : Convert STR to a string, push onto TOP
•-Q, --query : Query the stack by deep copying and pushing onto TOP
•-R, --real : Assert TOP to be a real
•-s NAME, --set=NAME : Sets TOP into PREV (obj.) with NAME
•-s , --set= : Sets TOP into PREV (obj.) at #
•-s -, --set=- : Sets TOP into PREV (obj.) at # from the end
•-S, --string : Assert TOP to be a string
•-t , --truncate= : Shrink TOP (arr.) to length #
•-t -, --truncate=- : Discard last # items from TOP (arr.)
•-T, --true : Assert TOP to be true
•-u FILE, --unquote=FILE : Write TOP (str.) to FILE without quotes
•-u -, --unquote=- : Write TOP (str.) to STDOUT without quotes
•-U, --unwind : Discard TOP from the stack
•-x, --extend : Append items from TOP to the end of PREV (arr.)
•-x, --extend : Set all values from TOP (obj.) into PREV (obj.)
•-X, --not : Invert the following assertion
•-y, --b64load : URL-safe Base64 decode TOP (str.), push onto TOP
•-Y, --b64dump : URL-safe Base64 encode TOP, push onto TOP

Extract the alg parameter from a JWE Protected Header:

$ jose fmt -j "$jwe" -Og protected -yOg alg -Su-
A128KW

List all JWKs in a JWKSet (one per line):

$ echo "$jwkset" | jose fmt -j- -Og keys -Af-
{"kty":"oct",...}
{"kty":"EC",...}

Change the algorithm in a JWK:

$ echo "$jwk" | jose fmt -j- -j '"A128GCM"' -s alg -Uo-
{"kty":"oct","alg":"A128GCM",...}

Build a JWE template:

$ jose fmt -j '{}' -cs unprotected -q A128KW -s alg -UUo-
{"unprotected":{"alg":"A128KW"}}

Nathaniel McCallum <npmccallum@redhat.com>

06/09/2026