I thought that was a zsh thing rather than an iTerm2 thing. You can use zsh in iTerm2 though.
while bashims may give additional features, readability and portability suffers. I much prefer scripts using a posixish #!/bin/sh and a strict subset of shell syntax. something like pdfx.
I use fish for scripting but run zsh for terminal. (fish had couple weirdness in day to day terminal use and zsh could do pretty much all fish could do with zplug.)
https://github.com/sorin-ionescu/prezto https://github.com/zsh-users/antigen See also: https://github.com/unixorn/awesome-zsh-plugins