云服务器Ubuntu18.04系统下成功下载R及rstudio，本地、网页均无法打开rstudio

云服务器Ubuntu18.04系统已经成功下载R，rstudio-server，本地，网页版均无法打开rstudio……崩溃了……期待各位专家们莅临指导 T_T

mengfei@iZ2zeh7tqthaheqrfl87z2Z:/root$ R

R version 4.1.1 (2021-08-10) -- "Kick Things"
Copyright (C) 2021 The R Foundation for Statistical Computing
Platform: x86_64-pc-linux-gnu (64-bit)
R is free software and comes with ABSOLUTELY NO WARRANTY.
You are welcome to redistribute it under certain conditions.
Type 'license()' or 'licence()' for distribution details.
Natural language support but running in an English locale
R is a collaborative project with many contributors.
Type 'contributors()' for more information and
'citation()' on how to cite R or R packages in publications.
Type 'demo()' for some demos, 'help()' for on-line help, or
'help.start()' for an HTML browser interface to help.
Type 'q()' to quit R.

mengfei@iZ2zeh7tqthaheqrfl87z2Z:/root$ rstudio-server verify-installation

Server is running and must be stopped before running verify-installation

mengfei@iZ2zeh7tqthaheqrfl87z2Z:/root$ rstudio

rstudio: command not found

网页版rstudio：