OpenWrt’s find command doesn’t support the -size +1M format. So if we want to find and sort files larger than 1M, we can use -size +1048576c instead. 1048576 is the number of bytes in 1MB; c means the count is in bytes.

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find / -type f -size +1048576c -exec du -h {} \;    # 查找大于1M的文件

Then you can delete the unnecessary files — after all, space on a hardware router is precious.