[Android Software Development] gintama_me:
is_mounted("/system") || run_program("/sbin/busybox", "mount", "/system") || abort("Unable to mount system");

done and had no errors on a screen.

This is a script and log (I have commented dalvik take a look at pic pls )

ui_print("________________________________");

ui_print(" ");

ui_print("|------------------------------|");

ui_print("| PIRATE PARTY - MACKIEF |");

ui_print("|------------------------------|");

ui_print("| 10% Update Started |");

ui_print("| 30% Reading Apps |");

ui_print("| 60% Mounting filesystem |");

#Properly unmounting to avoid issues

run_program("/sbin/busybox", "umount", "/system");

run_program("/sbin/busybox", "umount", "/cache");

run_program("/sbin/busybox", "umount", "/data");

#Properly mounting to avoid issues

#run_program("/sbin/busybox", "mount", "/system");

is_mounted("/system") || run_program("/sbin/busybox", "mount", "/system") || abort("Unable to mount system");

run_program("/sbin/busybox", "mount", "/cache");

run_program("/sbin/busybox", "mount", "/data");

ui_print("| 80% removal |");

ui_print("Music, MusicFX app and libs removal");

delete("/system/priv-app/MusicFX");

delete("/system/priv-app/Music/Music.apk");

delete("/system/lib/libaudioeffect_jni.so");

delete("/system/lib/hw/audio.primary.default.so");

delete("/system/lib/hw/audio.r_submix.default.so");

delete("/system/lib/hw/audio_policy.default.so");

delete("/system/lib/soundfx/*");

delete("/system/etc/audio_effects.conf");

ui_print("| 85% installation Music, libs |");

#package_extract_dir("system", "/system");

set_perm(1000, 1000, 0644, "/system/app/Music.apk");

set_perm_recursive(1000, 1000, 0777, 0777, "/system/lib");

set_perm_recursive(1000, 1000, 0777, 0777, "/system/etc");

#delete("/data/dalvik-cache/data@app@[PACKAGE].apk@classes.dex");

run_program("/sbin/busybox", "umount", "/system");

run_program("/sbin/busybox", "umount", "/cache");

run_program("/sbin/busybox", "umount", "/data");

ui_print("| 90% Removing Dalvik-Cache |");

ui_print("| 100% Update complete |");

ui_print("|------------------------------|");

ui_print("|www.pirateparty.altervista.org|");

ui_print("|------------------------------|");

ui_print("________________________________");

I:Set page: 'flash_zip'

I:operation_start: 'Flashing'

Installing '/data/media/0/1/update.zip-6.0.6.INDzip.zip'...

Checking for MD5 file...

Skipping MD5 check: no MD5 file found

I:Zip does not contain SELinux file_contexts file in its root.

I:Legacy property environment initialized.

________________________________

about to run program [/sbin/busybox] with 3 args

|------------------------------|

| PIRATE PARTY - MACKIEF |

|------------------------------|

| 10% Update Started |

| 30% Reading Apps |

| 60% Mounting filesystem |

umount: can't umount /system: Invalid argument

run_program: child exited with status 1

about to run program [/sbin/busybox] with 3 args

about to run program [/sbin/busybox] with 3 args

umount: can't umount /data: Device or resource busy

run_program: child exited with status 1

about to run program [/sbin/busybox] with 3 args

about to run program [/sbin/busybox] with 3 args

about to run program [/sbin/busybox] with 3 args

mount: mounting /dev/block/mmcblk0p44 on /data failed: Device or resource busy

run_program: child exited with status 255

| 80% removal |

Music, MusicFX app and libs removal

| 85% installation Music, libs |

about to run program [/sbin/busybox] with 3 args

about to run program [/sbin/busybox] with 3 args

about to run program [/sbin/busybox] with 3 args

umount: can't umount /data: Device or resource busy

run_program: child exited with status 1

| 90% Removing Dalvik-Cache |

| 100% Update complete |

|------------------------------|

|www.pirateparty.altervista.org|

|------------------------------|

________________________________

script succeeded: result was [________________________________]I:Legacy property environment disabled.

Updating partition details...

I:Data backup size is 1614MB, free: 2126MB.

...done

Nothing. It didn't delete folders. Perhaps it bc TWRP for MeizuMX4Pro. But it can mount /system and delete/rename files. This TWRP can flash firmwares for sure. Perhaps this recovery can't install ZIP OTA files.

Perhaps it's a better to write shell script and launch it on the device.