'pm2 flush' only supports single app

What's going wrong?

I found https://github.com/Unitech/pm2/issues/3270 while looking for a way to log multiple apps and that worked but then I noticed that flush does not support this.

I can get around it with pm2 flush appA && pm2 flush appB but just thought it would be nice to use the RegExp pattern.

How could we reproduce this issue?

Run the following:

pm2 flush "/(appA|appB)/"

Supporting information

$ pm2 report

--- PM2 report ----------------------------------------------------------------
Date                 : Tue Sep 07 2021 14:18:39 GMT-0500 (Central Daylight Time)
===============================================================================
--- Daemon -------------------------------------------------
pm2d version         : 5.1.0
node version         : 14.15.0
node path            : /Users/eliw00d/.nvm/versions/node/v14.15.0/bin/yarn
argv                 : /Users/eliw00d/.nvm/versions/node/v14.15.0/bin/node,/Users/eliw00d/Documents/GitHub/project/node_modules/pm2/lib/Daemon.js
argv0                : /Users/eliw00d/.nvm/versions/node/v14.15.0/bin/node
user                 : eliw00d
uid                  : 1220747810
gid                  : 1244359605
uptime               : 32min
===============================================================================
--- CLI ----------------------------------------------------
local pm2            : 5.1.0
node version         : 14.15.0
node path            : /Users/eliw00d/.nvm/versions/node/v14.15.0/bin/yarn
argv                 : /Users/eliw00d/.nvm/versions/node/v14.15.0/bin/node,/Users/eliw00d/Documents/GitHub/project/node_modules/pm2/bin/pm2,report
argv0                : /Users/eliw00d/.nvm/versions/node/v14.15.0/bin/node
user                 : eliw00d
uid                  : 1220747810
gid                  : 1244359605
===============================================================================
--- System info --------------------------------------------
arch                 : x64
platform             : darwin
type                 : Darwin
cpus                 : Intel(R) Core(TM) i9-9880H CPU @ 2.30GHz
cpus nb              : 16
freemem              : 588169216
totalmem             : 34359738368
home                 : /Users/eliw00d
===============================================================================

Start at the pm2 flush CLI entry point and reproduce the reported command pm2 flush "/(appA|appB)/" alongside the separate flush commands. Trace how the argument is matched to applications and verify that the regexp form flushes both appA and appB when the work is complete.