./mr_freeze.sh (freeze|thaw|prior_result) input
Blogpost-documentation generated by using
./mr_freeze.sh usage as a way to try to have all in one
place ;)
Source here : https://gist.github.com/jul/ef4cbc4f506caace73c3c38b91cb1ea2
A utility for comparing present scripts execution with past output
Action
freeze input
record the script given in input with ONE INSTRUCTION PER LINE to compare result for future use.
Except when **_OUTPUT** is set, output will automatically redirected to replay_${input}
thaw input
replay the command in input (a frozen script output) and compare them with past result
prior_result input
show the past recorded value in the input file
Quickstart
The code comes with its own testing data that are dumped in input
It is therefore possible to try the code with the following input :
$ PROD=1 ./mr_freeze.sh freeze input "badass" "b c"
to have the following output
✍️ recording: uname -a #immutable
✍️ recording: [ -n "$PROD" ] && echo "ok" || echo "ko" # mutable according to env variable
✍️ recording: date # mutable
✍️ recording: slmdkfmlsfs # immutable
✍️ recording: du -sh #immutable (kof kof)
✍️ recording: ssh "$A" 'uname -a'
✅ [input] recorded. Use [./mr_freeze.sh thaw "replay_input" "badass" "b c"] to replayofc, it works because I have a station called badass with an ssh server.
and then check what happens when you thaw the file accordingly.
$ ./mr_freeze.sh thaw "replay_input" "badass" "b c"
You have the following result:
👌 uname -a #immutable
🔥 [ -n "$PROD" ] && echo "ok" || echo "ko" # mutable according to env variable
@@ -1 +1 @@
-ok
+ko
🔥 date # mutable
@@ -1 +1 @@
-lun. 10 nov. 2025 20:21:14 CET
+lun. 10 nov. 2025 20:21:17 CET
👌 slmdkfmlsfs # immutable
👌 du -sh #immutable (kof kof)
👌 ssh "$A" 'uname -a'Which means the commands replayed with same output except date and the code checking for the env variable PROD and there is a diff of the output of the command.
Since the script is using subtituable variables ($3 … $10) being remapped to ($A … $H)
We can also change the target of the ssh command by doing :
$ PROD=1 ./mr_freeze.sh thaw "replay_input" "petiot"
which gives:
👌 uname -a #immutable
👌 [ -n "$PROD" ] && echo "ok" || echo "ko" # mutable according to env variable
🔥 date # mutable
@@ -1 +1 @@
-lun. 10 nov. 2025 20:21:14 CET
+lun. 10 nov. 2025 20:22:30 CET
👌 slmdkfmlsfs # immutable
👌 du -sh #immutable (kof kof)
🔥 ssh "$A" 'uname -a'
@@ -1 +1 @@
-Linux badass 6.8.0-85-generic #85-Ubuntu SMP PREEMPT_DYNAMIC Thu Sep 18 15:26:59 UTC 2025 x86_64 x86_64 x86_64 GNU/Linux
+FreeBSD petiot 14.3-RELEASE-p5 FreeBSD 14.3-RELEASE-p5 GENERIC amd64It’s also possible to change the output file by using _OUTPUT like this :
$ _OUTPUT=this ./mr_freeze.sh freeze input badasswhich will acknowledge the passed argument :
✅ [input] created use [./mr_freeze.sh thaw "this" "badass"] to replayAnd last to check what has been recorded :
$ ./mr_freeze.sh prior_result thiswhich gives :
👉 uname -a #immutable
Linux badass 6.8.0-85-generic #85-Ubuntu SMP PREEMPT_DYNAMIC Thu Sep 18 15:26:59 UTC 2025 x86_64 x86_64 x86_64 GNU/Linux
Status:0
--------------------------------------------------------------------------
👉 [ -n "$PROD" ] && echo "ok" || echo "ko" # mutable according to env variable
ok
Status:0
--------------------------------------------------------------------------
👉 date # mutable
lun. 10 nov. 2025 20:21:14 CET
Status:0
--------------------------------------------------------------------------
👉 slmdkfmlsfs # immutable
./mr_freeze.sh: ligne 165: slmdkfmlsfs : commande introuvable
Status:127
--------------------------------------------------------------------------
👉 du -sh #immutable (kof kof)
308K .
Status:0
--------------------------------------------------------------------------
👉 ssh "$A" 'uname -a'
Linux badass 6.8.0-85-generic #85-Ubuntu SMP PREEMPT_DYNAMIC Thu Sep 18 15:26:59 UTC 2025 x86_64 x86_64 x86_64 GNU/Linux
Status:0
--------------------------------------------------------------------------