On opening a terminal, pressing the "up" arrow key (zsh and bash's shortcut for "last entered command") reveals that a command of the form below was my most recent command. I never type anything of the sort and believe this only happens in RStudio.
Could I ask what the meaning and purpose of this command is? I especially want to make sure that such a command is intentional and I haven't downloaded malware from my Linux distribution's package repository (the signature seemed to be correct, though).
I'm using RStudio 2022.07.1.548 on Arch Linux (rstudio-desktop-bin obtained from the AUR), which to my understanding is not produced or maintained by RStudio officially (as some other Linux distros are). My terminal is zsh 5.9. I am using R version 4.2.1.
(apologies if this has been clarified elsewhere, I could not find an answer)
echo is a unix command to print things to the standard output so that they can be read by the user.
Therefore considered as a whole, this code writes 4 things to your terminal for you to read (when it is run). it will print the string 859B3DF8 , it will print 'histcontrol' i.e. control settings that determine how linux command history works, it will print the contents of /usr/bin/env and it will print the string 2D16B4FF
Yes, I completely understand that is what the command will print. My question was about what this string is being used for and why in RStudio that this apparently is my most recently entered command.
Environment variables are often an attack vector; I don't really think that's the case here and RStudio just wants to know the environment of my terminal for integration purposes, but wanted additional clarification to make sure this is the case.
Your hunch that RStudio is reading the environment is correct. RStudio uses this to save your environment so that if your session is unexpectedly ended, it can restore your environment from the backup.
There are a couple of things you can do to avoid this:
Enable the Bash setting that prevents commands with a leading space from getting included in the history; HISTCONTROL=ignorespace. RStudio prefixes its commands with a space in order to make it easier to discard them with this method.
Turn off RStudio's environment restoration feature entirely, so that these commands aren't issued at all. You can do this in Options -> Terminal -> Closing -> uncheck Save and Restore Environment Variables.