I have noticed that my shell buffers in Emacs (24.3.1) have (an extra) ".:" at the beginning of the $PATH variable on my Mac OS X (but not on my linux laptop that has the same . files), compared to my regular shell, which has it in the middle somewhere. Is this just me, or does Emacs on mac do this for some purpose? And can I prevent it? I don't think it has caused any actual problems, but it does cause warnings from RVM, and theoretically it has risks.
Thanks!
According to the emacs help entry for the shell command, the started shell gets the file ~/.emacs_SHELLNAME or ~/.emacs.d/init_SHELLNAME.sh as first command list (if one of those files exist). So you can modify the value of the PATH environment variable in one of those two files, but you should then check that your shell (configurable with the explicit-shell-file-name variable, the ESHELL environment variable or the shell-file-name variable, in that order) does not ignore commands that are issued during start-up.
Another reason may be that your (system-wide) configuration includes the current directory into the PATH value (you can check that with echo $PATH in a terminal), thus you would have to reconfigure your shell instead of emacs.
Considering security, having the current directory in the PATH does have the risk of unintentionally executing the wrong program (eg.: you have a self-written program named test and want to execute /usr/bin/test). That may cause some serious trouble, if that happens while working with super-user privileges.
Related
Backup, first.
Before attempting to resolve this, people are worried about $PATH changes breaking things. Backup your path with echo $PATH > $HOME/bak/conf/path.bak and remember (don't put any raw files into the bak dir). Confirm your backup with cat $HOME/bak/conf/path.bak.
A minimal $PATH!
My desired path is /usr/local/sbin:/usr/local/bin:/usr/sbin:/usr/bin.
This is a minimalist path that should break nothing on most default Linux installs (Backup, first).
I have a huge $PATH that is completely useless (like 120 lines of $PATH--caused by WSL [more later]). So far, I only know how to add to path and remove single directories from $PATH via seg.
Sounds like it should pop right up on search engines. I have a headache in my eye--:
how do I set $PATH to a raw string or purge it so I can append from null?.
Bonus points for anyone who can tell me how to set $PATH from the contents of a file!?
Best guess:
import sys, sys.path.insert(0, '/your/path')--!NO This did not work!
Temporary workaround:
You can move the path to a neutral file (or use whatever means you know) and replace / with / and then use sed to cut the unwanted part out:
PATH=$(echo "$PATH" | sed -e 's/:\/tons:\/of:\/unwanted:\/garbage$//')
Make sure you put everything you don't want between s/ and $//').
Where is this long $PATH coming from?
Related question: How to remove the Win10's PATH from WSL --$PATH is inherited every time you re-launch or perform some other actions such as possibly changing users or environments.
Why is this question different:
As if there isn't enough typing, S.O. has a nuisance dialog that asks me to write and explain why purging $PATH is different from removing one directory/path from $PATH.
Because a punch in the face isn't a kick in the butt.
If I'm understanding your question, you simply want to know how to set your Bash PATH to a fixed string (or erase it completely) and have it persist across restarts of the shell?
If so, then I'll start off by saying that this isn't recommended as it will break other things. If not now, then later.
But if you really want to set the PATH to a fixed value every time Bash starts ...
Short answer first:
Assuming fairly "default" startup files (where ~/.profile sources ~/.bashrc):
Edit your ~/.profile (or ~/.bash_profile in the rare case it exists) and add:
# Remove entirely
unset PATH
export -n PATH
# Optionally
export PATH=/new/pathItem1:/new/path/Item2
Adding this to the bottom of the file should override any other PATH modifications done previously. However, future application installations can make modifications below that, therefore overriding it.
In a very rare case where you have an interactive Bash session that isn't startup by a login shell, you could also make the same modifications to ~/.bashrc.
(Not necessarily required if the modification is the last thing called during startup, but) make sure that there are no other PATH adjustments in your ~/.bashrc or ~/.bash_profile.
More explanation:
Where is this long $PATH coming from?
Your path in Bash in WSL can potentially come from a few sources:
WSL's init process sets a default PATH for the starting application (shell). This is currently (in WSL 0.70.8):
/usr/local/sbin:/usr/local/bin:/usr/sbin:/usr/bin:/sbin:/bin:/usr/games:/usr/local/games:/usr/lib/wsl/lib
Since this is done before your ~/.profile runs, there's no need to worry about disabling it.
As you've pointed out, WSL automatically appends the Windows path to the Linux path so that you can launch Windows executables. This can be disabled using the method in the question you linked, but it's not necessary if you simply want to override the entire PATH. Setting the PATH in your ~/.profile comes after WSL sets it for the initial process (your shell).
Bash itself has a built-in, default path that is hardcoded into it for "fallback" in case no other path is passed in. This rarely ever takes effect. Most Linux systems are going to set the PATH through some other mechanism, meaning the fallback never gets activated. A typical Linux system will set the default PATH via /etc/environment, but this isn't used under WSL since the init mechanism mentioned above is needed instead.
If using Systemd or another init system in WSL, then Bash (and other POSIX shells) will process /etc/profile and files in /etc/profile.d when starting. These files may contain PATH modifications. Again, since these come before your ~/.profile, (re)setting the PATH to a fixed value will override any of these settings.
Finally, your ~/.profile or ~/.bash_profile (for login shells) and ~/.bashrc (for interactive shells are read. Typically, PATH modifications in these files look something like:
export PATH="/new/path/item:$PATH"
This prepends to the path, making that new item take priority over the previous items.
However, leaving out the existing :$PATH part will simply set it to a string literal.
It should be obvious, but if you do this without including the "normal" OS paths, you will be unable to call any command that isn't built in to Bash already with specifying its fully qualified path. For instance, ls will fail. Note that you can still:
$ ls
ls: command not found
$ /usr/bin/ls
# works
Also note that ~/.profile is called for login shells. It is possible, however, to tell WSL to launch Bash without reading ~/.profile:
wsl ~ -e bash --noprofile
The resulting shell will still have the default WSL path in this case.
I cannot use vcvarsall.bat from cygwin because cygwin overwrites environment variables (like PATH) and then the environment in cmd.exe, which is inherited from the cygwin BASH environment, finds the wrong cmake.exe.
Is there any pre-defined way to do this? Maybe without having to resort to opening a new shell window? Currently, I'm rewriting and stripping the entire PATH string. But now I have another issue: TEMP points to the wrong directory. I could just change that manually, but I really want it to adhere to original Windows behaviour.
Firstly, I'm using Mac OS X. Secondly, I am attempting to install something which says:
If you include this line (or source $CALDB/software/tools/caldbinit.sh
for Bourne shell users) in your .login file, then the CALDB will be
available to you every time you log in.
What exactly is the .login file? And where can it be found?
On *nix systems, each time you login, it looks for a file named .login and executes any commands it finds in the file. Much like when you start a new C shell, the system looks for a file named .cshrc and executes it.
Though OSX uses other ways to implement this functionality, .login is still recognized. Typically .login file includes a command to "source" (read and execute) a standard system login file that sets the standard PATH, TERM, and PROMPT variables. Others such as your CALDB installation want to be initialized at login time by inserting the appropriate source line:
source $CALDB/software/tools/caldbinit.sh
Note you may have to substitute the literal path for $CALDB in the path above since that var may not be initialized at the time of login when this script is run.
Addendum:
.login is typically in the home directory when using csh or tsch shells. If it's not there, you'll have to create it. However, depending on the version of OSX you are using you may have other options or different ways of achieving the same effect. Follow the documentation (link provided above) for the best option for your version of OS X.
In native emacs on windows, how can I specify environment variables for launching my shell inside emacs without modifying emacs' environment? In my specific case I'd like to set HOME to a cygwin-specific value for zsh without modifying where emacs thinks it's config file lives.
I've tried some things like changing my shell to env -u HOME ...\zsh.exe, but that seems to break (shell-command) (it appeared to involve argument order).
If this command existed, it would probably do what I want:
(setq explicit-zsh-environment '("HOME" nil))
I've read a bunch of related questions like (How can I run Cygwin Bash Shell from within Emacs?), but the unusual part for me is that all my config files are cygwin-ln-ed or windows-mklink-ed into a git repo and cygwin and windows take very different and incompatible approaches to symlinks.
Is this about running zsh as a shell inside Emacs (i.e. not about starting Emacs from a zsh shell), and having the environment that the inferior zsh process sees be different to the environment that Emacs has?
If so, you can bind the C-hv process-environment variable when you start a process. e.g.:
(let ((process-environment '("HOME=/tmp")))
(call-interactively 'shell))
$ echo $HOME
/tmp
From the Emacs manual:
Emacs sends the new shell the contents of the file ~/.emacs_shellname as input, if it exists, where shellname is the name of the file that the shell was loaded from. For example, if you use bash, the file sent to it is ~/.emacs_bash. If this file is not found, Emacs tries with ~/.emacs.d/init_shellname.sh.
So for zsh you would put inside ~/.emacs.d/init_zsh.sh something like:
export HOME=/tmp
Bash completion seems to work correctly for the PATH that is set when I start emacs, but if I change the PATH in an emacs shell buffer, I cannot seem to get Emacs to rethink its list of possible completions.
Is there some way to reinitialize Emacs view of the completions?
In a non-emacs shell, everything works as expected with the occasional hash -r thrown in for good measure.
Assuming you are using completion-at-point, there is a variable exec-path that maintains a list of the directories that are searched for executables. shell-command-completion, which is by default part of shell-dynamic-complete-functions, searches those locations.
You can update that variable with new locations to search for executables, eg. (push "<new-directory>" exec-path).