How to edit files on /system Android partition

Edit Android system files

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## Short reminder of how to edit a file in /system Android partition ##
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## Useful because only a buggy version of vim is available on device ##
## Last edit: 2017-05-30                                             ##
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## Mount /system as rw and pull Bloat Removal Script
adb root
adb shell
mount -o rw,remount,rw /system
exit
adb pull /system/addon.d/74-brs.sh

## Edit Bloat Removal Script locally
mv 74-brs.sh 74-brs.sh.2
vi 74-brs.sh.2            # edit line with 'rm -rf /system/priv-app/Gello' to 'rm -rf /system/priv-app/Jelly'; :wq

## Push back to system partition under a new temporary name
adb push 74-brs.sh.2 /system/addon.d/
adb shell
cd /system/addon.d        # check that permissions of 74-brs.sh and 74-brs.sh.2
ls -alg                   # are the same and file should be exact same size


## Set everything back to normal
mount -o ro,remount,ro /system
exit
adb unroot