# Help with how to better construct this message using GLOBAL context
**URL:** https://discourse.nodered.org/t/help-with-how-to-better-construct-this-message-using-global-context/100332
**Category:** General
**Created:** [7 February 2026 03:37 UTC](https://discourse.nodered.org/t/help-with-how-to-better-construct-this-message-using-global-context/100332 "2026-02-07T03:37:24Z")
**Posts on this page:** 10
**Page:** 1
### Author:  [@Trying\_to\_learn](https://discourse.nodered.org/u/Trying_to_learn)
#### Post date: [7 February 2026 03:37 UTC](https://discourse.nodered.org/t/help-with-how-to-better-construct-this-message-using-global-context/100332/1 "2026-02-07T03:37:24Z")
Ok: me being anal, or not. 🤷
I have this in an `exec` node:
`tail -n11 /media/pi/9020-9C27/events/commands_received.txt | cat`
Which is fair enough.
But I also have this in `global context`:
`event_paths` as `/media/pi/9020-9C27/events/` and
`log_paths` as `/media/pi/9020-9C27/logs/` (Ok not needed here, but....)
So I am wanting to _translate_ the `event_paths` into the command.
(As best I can explain it showing the _structure_)
`tail -n11 *globalContext_even_paths*commands_received.txt | cat`
The nodes:
```auto
[{"id":"74647831.e6bf18","type":"inject","z":"a3bd09a.b852978","name":"","repeat":"","crontab":"","once":false,"onceDelay":0.1,"topic":"","payload":"","payloadType":"date","x":310,"y":210,"wires":[["88ec09d0.6e1c28"]]},{"id":"88ec09d0.6e1c28","type":"exec","z":"a3bd09a.b852978","command":"ls -1 --file-type /media/pi/9020-9C27/logs/reboot/ | grep -v '/' | sed s/@$// | cat","addpay":false,"append":"","useSpawn":"false","timer":"","oldrc":false,"name":"Cat","x":470,"y":210,"wires":[["17917965.d43657","87a8c9d9.4f7f58"],[],[]]}]
```
Any ideas please?
---
### Author:  [@jbudd](https://discourse.nodered.org/u/jbudd)
#### Post date: [7 February 2026 09:12 UTC](https://discourse.nodered.org/t/help-with-how-to-better-construct-this-message-using-global-context/100332/2 "2026-02-07T09:12:48Z")
Why not construct your command line in a function or template node and pass the whole lot to exec as msg.payload, leaving `Command` in the exec node blank?
Incidentally, I'm pretty sure that your trailing `| cat` does nothing useful, though it does no harm either.
---
### Author:  [@Trying\_to\_learn](https://discourse.nodered.org/u/Trying_to_learn)
#### Post date: [7 February 2026 09:28 UTC](https://discourse.nodered.org/t/help-with-how-to-better-construct-this-message-using-global-context/100332/3 "2026-02-07T09:28:29Z")
I guess that would be the simple way.
Thanks.
I seem to have this ability to make simple things difficult for myself more times than I should.
I'll give it a go.
---
### Author:  [@Buckskin](https://discourse.nodered.org/u/Buckskin)
#### Post date: [7 February 2026 14:49 UTC](https://discourse.nodered.org/t/help-with-how-to-better-construct-this-message-using-global-context/100332/4 "2026-02-07T14:49:22Z")
> [@Trying\_to\_learn](#):
>
> /media/pi/9020-9C27/events/
Or
```auto
[{"id":"88ec09d0.6e1c28","type":"exec","z":"53a4dcf62732d6d9","command":"","addpay":"payload","append":"","useSpawn":"false","timer":"","winHide":false,"oldrc":false,"name":"Cat","x":1000,"y":1260,"wires":[["e3a8afb54bab0451"],["e3a8afb54bab0451"],["e3a8afb54bab0451"]],"info":"\"ls -1 --file-type \" & $globalContext(reboot) & \" | grep -v '/' | sed s/@$// | cat\""},{"id":"f0ea16b4c993cc86","type":"inject","z":"53a4dcf62732d6d9","name":"","props":[{"p":"payload"},{"p":"topic","vt":"str"}],"repeat":"","crontab":"","once":false,"onceDelay":0.1,"topic":"","payload":"\"ls -1 --file-type \" & $globalContext(\"reboot\") & \" | grep -v '/' | sed s/@$// | cat\"\t","payloadType":"jsonata","x":830,"y":1260,"wires":[["88ec09d0.6e1c28"]],"info":"\"ls -1 --file-type \" & $globalContext(reboot) & \" | grep -v '/' | sed s/@$// | cat\"\r\n\"tail -n11 \" & $globalContext(\"event_paths\") & \"commands_received.txt | cat\""}]
```
---
### Author:  [@Trying\_to\_learn](https://discourse.nodered.org/u/Trying_to_learn)
#### Post date: [7 February 2026 19:50 UTC](https://discourse.nodered.org/t/help-with-how-to-better-construct-this-message-using-global-context/100332/5 "2026-02-07T19:50:01Z")
(Mind blown.)
But it is (at this point in time) _MAGIC_.
The command
`"ls -1 --file-type " & $globalContext("reboot") & " | grep -v '/' | sed s/@$// | cat" `
is way beyond my skill set. (Not your problem)
But I can't draw a comparison to the _original_ command:
`tail -n11 *globalContext_even_paths*commands_received.txt | cat`
`ls` vs `tail` They are two very different commands.
I'll run off and do some digging and see what I learn.
But thanks.
---
### Author:  [@Trying\_to\_learn](https://discourse.nodered.org/u/Trying_to_learn)
#### Post date: [7 February 2026 20:05 UTC](https://discourse.nodered.org/t/help-with-how-to-better-construct-this-message-using-global-context/100332/6 "2026-02-07T20:05:12Z")
# IGNORE THIS REPLY Sorry, I goofed.
Left in because I'm dumb.
Ok, sorry I didn't declare this at the start.
The command is being _used_ in a `watch` node.
Monitoring file activity in the given directory.
Alas the `watch` node (both file and directory) doesn't have an input.
---
### Author:  [@jbudd](https://discourse.nodered.org/u/jbudd)
#### Post date: [7 February 2026 20:12 UTC](https://discourse.nodered.org/t/help-with-how-to-better-construct-this-message-using-global-context/100332/7 "2026-02-07T20:12:31Z")
> [@Trying\_to\_learn](#):
>
> `ls` vs `tail` They are two very different commands.
In your original post you talked about
`tail -n11 /media/pi/9020-9C27/events/commands_received.txt | cat`
which as you know prints the last 11 lines in the file.
But in your sample flow the exec node is set to run
`ls -1 --file-type /media/pi/9020-9C27/logs/reboot/ | grep -v '/' | sed s/@$// | cat`
which lists the files in the reboot directory, ignoring subdirectories and stripping any @ symbols off the end of the filename.
So they are indeed very different commands. 😄
Which one are you trying to parameterise with the global context variable?
Maybe you should share a bit more of the flow (not all of it please!)
---
### Author:  [@Trying\_to\_learn](https://discourse.nodered.org/u/Trying_to_learn)
#### Post date: [7 February 2026 20:26 UTC](https://discourse.nodered.org/t/help-with-how-to-better-construct-this-message-using-global-context/100332/8 "2026-02-07T20:26:02Z")
You are right.
I got confused. So many things happening.
Ignoring my incorrect post (number 5)....
I am wanting to display the last few lines of the reboot log file.
The _rub_ (for me) is that I am entering the entire path - which is fixed.
Small part of the code:
```auto
[{"id":"74647831.e6bf18","type":"inject","z":"a3bd09a.b852978","name":"","repeat":"","crontab":"","once":false,"onceDelay":0.1,"topic":"","payload":"","payloadType":"date","x":310,"y":210,"wires":[["88ec09d0.6e1c28"]]},{"id":"88ec09d0.6e1c28","type":"exec","z":"a3bd09a.b852978","command":"ls -1 --file-type /media/pi/9020-9C27/logs/reboot/ | grep -v '/' | sed s/@$// | cat","addpay":false,"append":"","useSpawn":"false","timer":"","oldrc":false,"name":"Cat","x":470,"y":210,"wires":[["17917965.d43657","87a8c9d9.4f7f58"],[],[]]},{"id":"17917965.d43657","type":"split","z":"a3bd09a.b852978","name":"","splt":"\\n","spltType":"str","arraySplt":1,"arraySpltType":"len","stream":false,"addname":"","x":670,"y":200,"wires":[["f8e85ffb.27a12","a2f4ed08.9b76d"]]},{"id":"f8e85ffb.27a12","type":"switch","z":"a3bd09a.b852978","name":"","property":"payload","propertyType":"msg","rules":[{"t":"nempty"}],"checkall":"true","repair":false,"outputs":1,"x":670,"y":250,"wires":[["8d28b379.4fc7b","4df38dde.8dd85c"]]},{"id":"4df38dde.8dd85c","type":"debug","z":"a3bd09a.b852978","name":"3","active":false,"tosidebar":true,"console":false,"tostatus":false,"complete":"payload","targetType":"msg","x":840,"y":250,"wires":[]}]
```
The `switch` node may not be needed. It is included .... yeah. I'm not sure.
But as it, it works.
I think it is to handle the case if the file is empty. But I 'm not sure it is the right way of doing it.
## So....
The _problem_ is that if ever I change the USB stick to another one.
I just edit the `global context` and don't need to also edit this node. (And others like it)
Probably as suggested in reply 2 I do it that way.
---
### Author:  [@Trying\_to\_learn](https://discourse.nodered.org/u/Trying_to_learn)
#### Post date: [7 February 2026 20:35 UTC](https://discourse.nodered.org/t/help-with-how-to-better-construct-this-message-using-global-context/100332/9 "2026-02-07T20:35:44Z")
Ok, expansion on things.
Here is another (sorry) bit of the code.
```auto
[{"id":"74647831.e6bf18","type":"inject","z":"a3bd09a.b852978","name":"","repeat":"","crontab":"","once":false,"onceDelay":0.1,"topic":"","payload":"","payloadType":"date","x":310,"y":210,"wires":[["88ec09d0.6e1c28"]]},{"id":"88ec09d0.6e1c28","type":"exec","z":"a3bd09a.b852978","command":"ls -1 --file-type /media/pi/9020-9C27/logs/reboot/ | grep -v '/' | sed s/@$// | cat","addpay":false,"append":"","useSpawn":"false","timer":"","oldrc":false,"name":"Cat","x":470,"y":210,"wires":[["17917965.d43657","87a8c9d9.4f7f58"],[],[]]},{"id":"17917965.d43657","type":"split","z":"a3bd09a.b852978","name":"","splt":"\\n","spltType":"str","arraySplt":1,"arraySpltType":"len","stream":false,"addname":"","x":670,"y":200,"wires":[["f8e85ffb.27a12","a2f4ed08.9b76d"]]},{"id":"a2f4ed08.9b76d","type":"debug","z":"a3bd09a.b852978","name":"2","active":true,"tosidebar":true,"console":false,"tostatus":false,"complete":"payload","targetType":"msg","x":840,"y":200,"wires":[]},{"id":"f416f19bd14acba1","type":"inject","z":"a3bd09a.b852978","name":"","props":[{"p":"payload"},{"p":"topic","vt":"str"}],"repeat":"","crontab":"","once":false,"onceDelay":0.1,"topic":"","payload":"","payloadType":"date","x":1010,"y":140,"wires":[["3b8e8db1663c4cfe"]]},{"id":"3b8e8db1663c4cfe","type":"change","z":"a3bd09a.b852978","name":"command","rules":[{"t":"set","p":"payload","pt":"msg","to":"\"ls -1 --file-type \" & $globalContext(\"reboot\") & \" | grep -v '/' | sed s/@$// | cat\"\t","tot":"jsonata"}],"action":"","property":"","from":"","to":"","reg":false,"x":1180,"y":140,"wires":[["f84266302b2910d0"]]},{"id":"f84266302b2910d0","type":"exec","z":"a3bd09a.b852978","command":"","addpay":"payload","append":"","useSpawn":"false","timer":"","winHide":false,"oldrc":false,"name":"","x":1400,"y":140,"wires":[["17917965.d43657"],[],[]]}]
```
Desired.
What the new code gives me.
I'll see if I can work out where the problem is.
I'm guessing it is getting a list of all files rather than the one I want.
# AH!
Removing the wire between the `change` and the `exec` node (on the right) and replacing it with a `debug` I get this strange output:
But the _original_ command in the_original_ `exec` node is this command:
`ls -1 --file-type /media/pi/9020-9C27/logs/reboot/ | grep -v '/' | sed s/@$// | cat`
Slight difference.
Confused.
# Ah2!
Is this this what should be in the `change` node?
`"ls -1 --file-type " & $globalContext("log_path") & "reboot | grep -v '/' | sed s/@$// | cat" `
That seems to be giving me the expected result.
## RESOLVED!
Thanks folks.
---
### Author:  [@system](https://discourse.nodered.org/u/system)
#### Post date: [21 February 2026 20:35 UTC](https://discourse.nodered.org/t/help-with-how-to-better-construct-this-message-using-global-context/100332/10 "2026-02-21T20:35:46Z")
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