I have a problem. Universally, my experience working in Unix systems has been that, by the time you are ready to place an executable "thing" in a bin folder for global access, you have decided to #! the file with the requisite interpreter:
#!/bin/awk
#!/bin/bash
#!/bin/perl
#!/bin/python3.8
#!/bin/whatever
And, although it is fine to have clutter at the local scope, when one places an executable in the bin folder, it should have:
A POSIX CLI interface
No discernible language tags or what have you
This is because it is now intended to be used for difficult work that requires forgetting about the details of this or that language: one now needs to think in terms of the functions as if the composable units are part of a consistent language, rather than a dozen different languages from a dozen different expert contributors.
This is the "genius" of the Unix/Linux/Posix architecture.
Anyways, when structuring my python projects, the end game is copying python executables to a global source on the path -- whether that "global" source is a pretend global source in my home directory (i.e., ~/.mytools/bin or the actual global path, /usr/bin or something like that -- and generally I want my python executables to have the same "game feel" as C executables, perl executables, BASH/ZSH/etc. executables.
In that vein, I knock off the extensions from my scripts and executables when they go in the bin. There is no need to know, from my usage perspective, what anything is made of when I go to use it.
However, streamlit requires me to re-append the .py to the file in the global path in order to run with streamlit run. This is a case of the library reaching up out of its useful value and holding me hostage, from my perspective, unless I violate best practices when extending the bin folder with python executables.
This means I have to create special logic to handle just streamlit, and that is really a kerfluffle. I have to either: change the way I handle all executables, or hardcode just the executable that will be run with streamlit. That means that, all of a sudden, I have an arbitrary name in my meta-control code for my project.
That is bad. Why? because I have to remember that I did it, and remember to change it if I change the executable name. I also have to remember to add to it if I add another streamlit executable.
Alternatively, I can copy all my exes made with python into the root bin folders with their .py extensions, which is not what I wanted to do.
How does one bypass this issue in streamlit?
If bin/sometool needs to be invoked with Streamlit via streamlit run bin/sometool, it seems like you're already exposing "meta-control code" to users of your bin script, right?
Instead, would this solve your problem?
bin/sometool:
#!/bin/bash
DIR=$(dirname "$0")
streamlit run "$DIR"/the_actual_script.py
(Where the_actual_script.py sits inside bin, but has chmod -x so that it's not directly executable.)
Related
I have a configure script to set up some paths for my R package during installation. I wish to edit a file based on some conditions. Is there any way to edit a file from within the configure.ac? It would be great if the solution is provided for all operating systems.
Is there any way to edit a file from within the configure.ac?
configure.ac is not executable, but I suppose you mean that you want the configure script generated from it to edit a file. The configure script is a shell script, and you can cause arbitrary shell code to be included in it, more or less just by including that code at the corresponding point in configure.ac.
The question, then, is how you would automate editing a file with a shell script. There is a variety of alternatives, but sed is high on my list. You will find it on every system that can support Autoconf configure scripts, because such scripts use it internally.
On the other hand, this sort of thing is one of the main activities of a configure script, in the form of creating files (especially makefiles, but not limited to those) from templates. You should consider building your target file of interest from a template in this way, instead of making custom-programmed edits to a file packaged in your program distribution. This would involve
setting output variables containing the chosen content for the parts of the file that need to be configured;
designating the target file as one for configure to build; and
providing the template, maybe by taking a complete example file and replacing each variable part with a reference to the appropriate #output_variable#.
I'm adapting an existing program to use Autotools for its build, but the resulting process depends on an environment variable. Is there a way to permanently set this environment variable during the build or installation process?
The program is intended to be used by Unix users and I could try to concatenate an export command directly to the .bashrc file and warn the user in case it fails because most of them will actually just use Ubuntu to run it (it's a relatively simple program that targets students), but I'd like to know if there's a more portable way to do this.
That's what I wouldn't like to do:
export VAR=/my/totally/not/hardcoded/path >> $HOME/.bashrc
Sorry to come to this late, but all of the answers to date are shockingly ... incomplete.
Building and installing software are both core use cases for the Autotools, and the installation part can absolutely involve adding or modifying files that affect user environments. If the software is installed by a user with sufficient privilege, then such effects can absolutely be applied to all system users, though the details may vary a bit from system to system (and the Autotools can help with that, too!).
For example, on RedHat-family Linuxes such as RedHat Enterprise, Fedora, Oracle Linux, and various others, you can drop an appropriately named file in /etc/profile.d, and the commands in it will automatically be read and executed by every login shell. Setting environment variables for all users is one of the common uses of this feature. I'm uncertain about Debian-family Linuxes such as Ubuntu, but it is always possible to modify file /etc/profile instead to have the same effect, and you absolutely can write an Automake install hook to do that.
Or for an altogether different approach, you can always provide a wrapper script around your program that sets the needed environment variables (supposing that the point is other than to add a directory to the PATH so as to find the program in the first place). In that case, you can even install the main program in a location that is not ordinarily in the path, so that users don't accidentally run it directly. This mechanism has the advantage that the environment variables are scoped to a run of the program, not a whole login session, but the disadvantage that users cannot override them.
I guess, no.
Autotools are about building your program, not about environment setup for the program to run. That's what users/admins are supposed to do. (Well I can imagine doing this, but I really don't want to try to figure it out, because the idea itself seems broken to me)
If your program REALLY needs some environment variable during run-time, then you should patch your sources for your application to test if the variable exists, and set one to default desired value, if it doesn't. Another idea is to enforce usage of an obligatory command line switch to pass the value in.
It's not clear what this has to do with autotools (or any other build system). No build system, by itself, can arrange for an env var to be present when the program it builds is run at a later tiem.
One solution is for your program to have a hardcoded default value for the var which is used if the environment var isn't present when the program starts running. Another frequently used solution is to name your binary something like myprog.bin and install a shell script named myprog which sets up the environment before doing exec myprog.bin.
I'm adapting an existing program to use Autotools for its build, but the resulting process depends on an environment variable. Is there a way to permanently set this environment variable during the build or installation process?
You've not been very concrete about what the program is (e.g. is the program a daemon? A user program?) or the nature of the environment variable dependency (e.g. is it another program? A mount point? A URL? A DB connection string?). Being more specific might give a better answer for you.
Anyway, autotools is not likely to offer any feature to help: It's a build system. Depending on the nature of your environment variable dependency, you're likely going to need package management (if you package it) or system administration level setup.
Since you think your primary user base is on Ubuntu this help page might give you some ideas.
I'm a freshman, and I created a server with my roomates in order to practice in maintaining a server.
We installed CentOS7. And I would like to ask how I can install a tool for everyone to use?
More particularly, we want to install Cromwell. But since, they don't have instructions on how to install on Unix, I downloaded Linuxbrew and installed it like this.
The downside is that it's not visible to the other users connected to the servers.
I know this is a noob question, but any response would be appreciated.
A standard unix machine has programs (tools and so on) installed in predefined directories like /bin, /usr/bin, perhaps /usr/local/bin. Which to choose is another matter, probably you want /usr/bin. Also the environ variable PATH plays a role.
Into the chosen directory there should be a file representing the "tool". You can put a copy of the executable file in that directory, and set (or check) its permissions. Execution permission can be granted to all users, or only some, it depends. In other words,
/home/me/.linuxbrew/Cellar/cromwell
is not a good place for a "system" tool or app; you should copy that executable in /usr/bin, set ownership (perhaps to root?) with chown, and set the correct permissions with chmod.
You can make a hard link of your executable into the directory; this saves space, but also means that there is only one copy of the executable. Having two different copies (the "stable" one, and the other one you can fiddle with) can be handy.
After the executable is reachable and executable from the chosen users, maybe it needs some support files. To find them, it can rely on fixed locations, or some environment variable, or some configuration file. But all these things are outside of the scope of the question.
Try this command:
you#machine$ sudo chmod [who][op][permissions] filename
"who" refers to the users that have a particular permission: the user ("u"), the group ("g"), or other users ("o", also known as "world"). "op" determines whether to add ("+"), remove ("-") or explicitly set ("=") the particular permissions. "permissions" are whether the file should be readable ("r"), writable ("w"), or executable ("x"). As an example:
you#machine$ chmod o+x file
will add executable permission for others to file.
I have an application that updates some files in Unix server. Since I cannot modify this application, is there any way I can make sure that these files are copied before each update so I can have a history of the changes?
Is there a way/tool in Unix so I can do that?
If on Linux (specifically) you could use inotify(7) facilities (perhaps via incrontab ...)
Alternatively, you might run periodically (thru some crontab(5) entry) a script doing some make with your particular Makefile (since GNU make is designed to care about timestamps) managing e.g. backups. Or you could periodically run some rsync command.
However, it smells like you need some revision control (also known as version control system). I strongly recommend git; you could use it before and after running your application (e.g. write some wrapping shell script doing that).
But there is probably no universal solution (e.g. what if the monitored application is keeping a file descriptor opened for a long time, and write the file little by little...). You should explain much more what is happening and what do you want ...
Is it possible to create our own unix commands?
For example: we have ls -ltr,cd,mkdir etc which perform certain actions. I want to create a similar command which would save username-password into a table in database. I'm kinda new to unix. Any suggestions?
Yes, it is easy to create your own commands that do jobs that you find useful. You can implement them in a variety of languages, from shell to Perl to C and on and on.
The only significance to the standard commands are that they are installed (usually) in /bin or /usr/bin rather than anywhere else, and they do jobs that are defined by a standard (often POSIX). Often, people place locally created commands in /usr/local/bin; others will create themselves a directory $HOME/bin and put their personal commands there. You simply need to ensure that these directories are on your PATH.
In my $HOME/bin directory (depending on which machine I'm looking at), I have from 46 commands (on this machine) up to about 500 on my main work machines. The commands do different jobs; the names are mnemonic to me (and generally not to other people). Some commands are polished and ready for production use anywhere (and these have manual pages, almost by definition of being production-ready). Others are quick hacks assembled for a quick-and-dirty job. Some of the quick hacks are removed; some get polished; some get stashed away in case I need to do something similar in the future. Only the trivial don't go under version control.
On this machine (which I only use casually and not really for development work), I have 9 shell scripts, 4 Perl scripts, and the rest are executables (Git and Go, mainly). On my main machines, I have many more shell and Perl scripts and proportionately fewer C programs. I have few Python scripts since I learned Perl first and I'm not as fluent in Python. I've been writing and collecting these scripts for a long time; the oldest versions of the oldest programs date back to about 1987.