Shell integration

The composed environment reaches your shell in one of two ways: a hook that nem activate installs for interactive use, or nem exec and nem env for scripts and CI. Neither uses shims; a package is on PATH only while it applies.

There are two ways to bring the composed environment into your work: a shell hook for interactive, day-to-day use, and nem exec / nem env for scripts and CI. Neither uses shims — a package is only on your PATH for as long as it applies.

Installing the hook

nem activate      # zsh or bash
exec $SHELL

nem activate [zsh|bash] appends a managed block to .zshrc or .bashrc, between # >>> nem >>> and # <<< nem <<< markers. nem deactivate removes it. Restart the shell (exec $SHELL) so the block takes effect.

Use nem activate --print to print the block to stdout instead of installing it — also the default whenever stdout isn't a terminal, so eval "$(nem activate --print)" works from another program's init script.

What the hook does

The installed block:

• Saves the shell's original PATH once, before nem starts changing it;
• Registers a hook that re-evaluates eval "$(nem env --shell <shell>)": zsh's chpwd runs it on every cd, bash's PROMPT_COMMAND before every prompt;
• Wraps the nem command so use, unuse, lock, sync, and update re-apply the environment immediately, without waiting for the next directory change;
• Sources nem's shell completions.

Leaving restores everything

The script that nem env prints tracks every variable it manages, together with the value — or absence — it had before nem touched it. Leaving a project, or deactivating nem altogether, restores each one exactly: variables nem changed go back to their saved value, and variables nem set that didn't exist before are unset. PATH entries are deduplicated on the way in, so re-evaluating the hook repeatedly never grows PATH.

Scripts and CI

Outside an interactive shell, two commands give you the same composed environment without installing anything:

nem exec -- <cmd> [args...]   # run one command in the composed environment
nem env --shell bash          # print the script to eval instead

nem exec runs the command as a child process and exits with its exact status, which makes it the one to reach for in scripts and CI steps. nem env prints the shell script that applies the environment; eval it when you need the environment in the current shell rather than a subprocess.

Related

• nem activate, nem deactivate
• nem env, nem exec
• Environment variables