Is it possible to write a command inside sbt's shell using multiple lines?
For example, suppose I'm inside the sbt project for scalac itself:
$ git clone git#github.com:scala/scala.git
$ cd scala
$ sbt
> run file1.scala file2.scala file3.scala
Can I pass arguments to the run command on multiple lines? In bash, opening a single ' or a double quote ", or writing a \ at the end of a line allows command to spawn across multiple lines, is there an equivalent feature in sbt?
Related
I am writing a perl script, and I want to run a simple shell command to use a certain version of NVM:
Here is my code snippet:
print "\n*** Switching to correct nvm environment for dashboard builds\n";
system("nvm use 8.12.0") == 0 or die $?;
But I am getting the following error:
Can't exec "nvm": No such file or directory
Can someone help?
Update (June 30, 2021):
I also tried adding the command:
my $nvm_version = "8.12.0";
system ("bash", "-lic", "nvm use $nvm_version");
But nothing happens:
I'm not familiar with nwm, but I think I get the gist of what it does. And if so, the attempt is fundamentally flawed. Even if you fixed this to run the proper shell so that nvm could run, I believe all the tool does is change the shell's environment variables, a shell you immediately exit. This means it would have no effect even if if it ran successfully.
Again, it this tool does what I think it does, such tool are meant to be used in interactive shells. In other instances, you simply use the path the to correct executable instead of relying on the PATH.
With that in mind, you can use the following to run the command in bash:
# Non-interactive shell.
system("bash", "-c", "nvm use 8.12.0")
or
# Interactive shell.
# This is improper and fragile as interactive shells
# often create aliases that override basic commands.
system("bash", "-ic", "nvm use 8.12.0")
Just to reiterate, at least one of these will allow the command to run (if it normally works from bash), but I believe it's unlikely this will produce the results you expect.
The nvm command is shell function which is different from a shell command. Also the nvm command is not an exported function so it will not be seen by sub shells. For example, in Bash shell:
$ nvm ls
-> v15.0.1
$ my-test-script.sh
./my-test-script.sh: line 3: nvm: command not found
where my-test-script.sh is:
#! /bin/bash
nvm use 16.4
The error nvm: command not found is because nvm is not exported. I can source the script in the current shell context to make it work:
$ source my-test-script.sh
Now using node v16.4.0 (npm v7.18.1)
$ node --version
v16.4.0
So a Perl script cannot change the node version of the current shell, but it can calculate the version and pass it back to shell, which can set the version. For example:
$ nvm use $(perl -E'$v=15.0; print $v')
Now using node v15.0.1 (npm v7.0.3)
I am bit confused with commands in kubectl. I am not sure when I can use the commands directly like
command: ["command"] or -- some_command
vs
command: [/bin/sh, -c, "command"] or -- /bin/sh -c some_command
I am bit confused with commands in kubectl. I am not sure when I can use the commands directly
Thankfully the distinction is easy(?): every command: is fed into the exec system call (or its golang equivalent); so if your container contains a binary that the kernel can successfully execute, you are welcome to use it in command:; if it is a shell built-in, shell alias, or otherwise requires sh (or python or whatever) to execute, then you must be explicit to the container runtime about that distinction
If it helps any, the command: syntax of kubernetes container:s are the equivalent of ENTRYPOINT ["",""] line of Dockerfile, not CMD ["", ""] and for sure not ENTRYPOINT echo this is fed to /bin/sh for you.
At a low level, every (Unix/Linux) command is invoked as a series of "words". If you type a command into your shell, the shell does some preprocessing and then creates the "words" and runs the command. In Kubernetes command: (and args:) there isn't a shell involved, unless you explicitly supply one.
I would default to using the list form unless you specifically need shell features.
command: # overrides Docker ENTRYPOINT
- the_command
- --an-argument
- --another
- value
If you use list form, you must explicitly list out each word. You may use either YAML block list syntax as above or flow list syntax [command, arg1, arg2]. If there are embedded spaces in a single item [command, --option value] then those spaces are included in a single command-line option as if you quoted it, which frequently confuses programs.
You can explicitly invoke a shell if you need to:
command:
- sh
- -c
- the_command --an-argument --another value
This command is in exactly three words, sh, the option -c, and the shell command. The shell will process this command in the usual way and execute it.
You need the shell form only if you're doing something more complicated than running a simple command with fixed arguments. Running multiple sequential commands c1 && c2 or environment variable expansion c1 "$OPTION" are probably the most common ones, but any standard Bourne shell syntax would be acceptable here (redirects, pipelines, ...).
I am trying to run Scala in TextMate. I have created a new variable TM_SCALA and set it to the path which I obtained on executing the following command on the terminal
which scala
But when I try to run a Scala program, I get the error
Run Script: line 4: scala: command not found
This is the run script
#!/usr/bin/env bash
[[ -f "${TM_SUPPORT_PATH}/lib/bash_init.sh" ]] && . "${TM_SUPPORT_PATH}/lib/bash_init.sh"
scala -classpath . -savecompiled "$TM_FILEPATH"
I am unable to understand the problem. Thanks in advance.
Make sure you have scala downloaded.
update PATH variable in TextMate preferences. Append scalac path there.
Add a new command (or replace the 'run script' one) with this:
#!/usr/bin/env ruby -w
cmd = ENV['SCALA_HOME'] + "/scala -nocompdaemon -howtorun:script '" + ENV['TM_FILEPATH'] + "'"
result = "" + `#{cmd}`
puts "#{result}"
That assumes that you have a SCALA_HOME environment variable set to something like this:
export SCALA_HOME="/path/to/my/scala/scala-2.11.4/"
I'm using the Scala (2.10.3) Process object to run commands. The docs show me how to run a command and then capture the standard output, but I'm running s3cmd and want to see upload progresses. How can I capture the output as if the command were running in a terminal?
Solution:
"s3cmd sync --recursive --delete-removed --progress local/ s3://remote" ! ProcessLogger(line => log.info(line))
Line at a time:
http://www.scala-lang.org/api/2.10.3/#scala.sys.process.ProcessLogger
for vanilla stdout
https://github.com/s3tools/s3cmd/blob/master/S3/Progress.py
In python, I can run a script and enter interactive mode in the context of that script. This lets me mess with global variables and what not to examine program state.
$ python -i hello.py
Can I do this with Coffeescript? I've tried the following:
$ coffee -i hello.coffee
doesn't load hello.coffee. It's equivalent to coffee -i
$ cat hello.coffee | coffee -i
runs the script line by line in REPL but ends REPL after the EOF.
I've recently started a project to create an advanced interactive shell for Node and associated languages like CoffeeScript. One of the features is loading a file or string in the context of the interpreter at startup which takes into account the loaded language.
http://danielgtaylor.github.com/nesh/
Example:
# Load a string
nesh -c -e 'hello = (name) -> "Hello, #{name}"'
# Load a file
nesh -c -e hello.coffee
Then in the interpreter you can access the hello function. Also a good idea to create an alias in bash:
alias cs='nesh -c'
cat foo.coffee - | coffee -i
tells cat to first output your code and then output stdin, which gives you what you're looking for I think.
I am confronted with this problem as well. The one provide by #int3 doesn't solve this problem, for CoffeeScript is one indentation based language. stdin will pass the code line by line, but the repl is not smart enough to realize this. Since you post this question, I suggest you create one issue (feature request) on CoffeeScript