How do i display the output of systemd journalctl in json?

pangolinsos

Output in json one line.

$ journalctl -u postfix.service -o json
{ "__CURSOR" : "s=50dd9f837d0443828a9615806689fafd;i=ed;b=be3520dd2daf4ec4b24ce31885d8de37;m=38c62a7;t=5
{ "__CURSOR" : "s=50dd9f837d0443828a9615806689fafd;i=102;b=be3520dd2daf4ec4b24ce31885d8de37;m=39db7d4;t=
{ "__CURSOR" : "s=50dd9f837d0443828a9615806689fafd;i=103;b=be3520dd2daf4ec4b24ce3

Output in json over multiple lines, know as json-pretty.

$ journalctl -u postfix.service -o json-pretty
{
        "__CURSOR" : "s=50dd9f837d0443828a9615806689fafd;i=ed;b=be3520dd2daf4ec4b24ce31885d8de37;m=38c62
        "__REALTIME_TIMESTAMP" : "1549192590410951",
        "__MONOTONIC_TIMESTAMP" : "59531943",
        "_BOOT_ID" : "be3520dd2daf4ec4b24ce31885d8de37",
        "PRIORITY" : "6",
        "_UID" : "0",
        "_GID" : "0",
        "_MACHINE_ID" : "6dee5c9f241a493fb69d3d375c4d59fa",
        "SYSLOG_FACILITY" : "3",
        "SYSLOG_IDENTIFIER" : "systemd",
        "_TRANSPORT" : "journal",
        "_PID" : "1",
        "_COMM" : "systemd",
...
...
...

Other output formats from Man page.

       -o, --output=
           Controls the formatting of the journal entries that are shown. Takes one of the following
           options:

           short
               is the default and generates an output that is mostly identical to the formatting of
               classic syslog files, showing one line per journal entry.

           short-iso
               is very similar, but shows ISO 8601 wallclock timestamps.

           short-precise
               is very similar, but shows timestamps with full microsecond precision.

           short-monotonic
               is very similar, but shows monotonic timestamps instead of wallclock timestamps.

           verbose
               shows the full-structured entry items with all fields.

           export
               serializes the journal into a binary (but mostly text-based) stream suitable for
               backups and network transfer (see Journal Export Format[1] for more information).

           json
               formats entries as JSON data structures, one per line (see Journal JSON Format[2] for
               more information).

           json-pretty
               formats entries as JSON data structures, but formats them in multiple lines in order
               to make them more readable by humans.

           json-sse
               formats entries as JSON data structures, but wraps them in a format suitable for
               Server-Sent Events[3].

           cat
               generates a very terse output, only showing the actual message of each journal entry
               with no metadata, not even a timestamp.