When creating an accoutn in conversations the account data often is nor well remebered and some servers do not provide the option to retrieve the missing information. This worked today for two people that wanted to replace the f-droid version by the one from play store and reuse their accounts after the fresh installation.
#!/bin/sh
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# howto backup conversations account data
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#activate developer mode
#activate android debugging
#connect via usb
#test with `adb shell`, if that fails resume until it works
adb shell -x exit 0 && echo "[OK] debuggin is enabled" || echo "[KO] activate android debugging first!" && exit 1
echo "trying to backup of Conversations …"
adb backup -apk -obb eu.siacs.conversations -f conversations.ab
echo "create a copy without custom header"
dd if=conversations.ab bs=1 skip=24 > conversations.enc
echo "add standardized header"
printf "\x1f\x8b\x08\x00\x00\x00\x00\x00"|cat - conversations.enc|gunzip -c > conversations.tar
echo "unpack archive"
tar xf conversations.tar
echo "copy sqlite db"
cp ./apps/eu.siacs.conversations/db/history ./history.sqlite
echo "delete obsolete files"
rm -fR ./apps ./conversations.enc
echo "./history.sqlite contains the account data in the table with that name"