I want to test a unix command. More specifically the "Cat" command. I want to be able to get test data for this.
How do I go about doing this?
(Newbie to computer science)
I'll be using terminal
Depending on the operating system you are on you could type this in a command prompt or terminal.
If you are on OSX or a Linux derivative you'll need the terminal, if you are on Windows you'll need Cygwin to perform this action.
When you want to test commands that are possibly dangerous it's always best to try these in a virtual environment like Virtual Box
You could use any data for the cat command, if you're setup you could use the /etc/issue file with cat /etc/issue to print your distribution information (This is GNU/Linux specific).
Be sure to read the CAT manual page
Related
How does R's built-in system() function know where to look to invoke some arbitrary OS command specified by the command argument? For example, if I homebrew install some_command_line_program, how does R's system() function know where it is located when I type:
cmd <- "some_complicated_code_from_some_command_line_program"
system(cmd, wait=FALSE)
In other words, how is R smart enough to know where to look without any user input? If I compile from source via Github (instead of homebrew install), would system() also recognize the command?
What system does depends on your OS, you've not told us (although you've given us some clues...).
On unix-alike systems, it executes it as a command in a bash shell, which searches for the first match in the directories on the $PATH environment variable. You can see what that is in R:
> Sys.getenv("PATH")
[1] "/usr/local/heroku/bin:/usr/local/heroku/bin:/usr/local/sbin:/usr/local/bin:/usr/sbin:/usr/bin:/sbin:/bin:/usr/games:/usr/local/games:/nobackup/rowlings/NEST4B"
In Windows, it does something else.
You can get a full path to whatever it might run with Sys.which, which uses the systems' which command on unixes and fakes it on Windows. Read the help for more.
If you compile something from source then it will be found if the file that runs the command (a shell script, an executable, a #!-script in any language) is placed in a folder in your $PATH. You can create a folder yourself, say /home/user/bin, put your executables in there, add that to your $PATH, and (possibly after logging out an in again, or restarting R, or just firing up a new shell...) then R will find it.
Hej,
When I try to call QIIME with a system call from R, i.e
system2("macqiime")
R stops responding. It's no problem with other command line programs though.
can certain programs not be called from R via system2() ?
MacQIIME version:
MacQIIME 1.8.0-20140103
Sourcing MacQIIME environment variables...
This is the same as a normal terminal shell, except your default
python is DIFFERENT (/macqiime/bin/python) and there are other new
QIIME-related things in your PATH.
(note that I am primarily interested to call QIIME from R Markdown with engine = "sh" which fails, too. But I strongly suspect the problems are related)
In my experience, when you call Qiime from unix command line, it usually creates a virtual shell of it`s own to run its commands which is different from regular system commands like ls or mv. I suspect you may not be able to run Qiime from within R unless you emulate that same shell or configuration Qiime requires. I tried to run it from a python script and was not successful.
How am i able to execute UNIX commands on my PC Command prompt? Note i do not have cygwin installed, although i was going to before i discovered this.
This is a development machine so i have a lot installed on it like ruby, python, git, github, node and so on.
What does this mean? can i use this without cygwin?
Here is a list of programs installed on my PC program list
How am I able to execute UNIX commands on my PC Command prompt?
You can use the where command in a cmd shell to find out the exact location of your Unix commands, for example:
where ls
This assumes, of course, that ls is located somewhere in your current PATH.
The location returned will show you in which directory your Unix commands are installed and may be enough for you to determine how they were installed.
The where command is roughly equivalent to the Unix which command.
By default, the search is done in the current directory and in the
PATH.
Syntax
WHERE [/r Dir] [/q] [/f] [/t] Pattern ...
WHERE [/q] [/f] [/t] [$ENV:Pattern
Source where
Further Reading
An A-Z Index of the Windows CMD command line - An excellent reference for all things Windows cmd line related.
where - Locate and display files in a directory tree.
Running Unix commands in windows can be done by having a tool like Cygwin which has those commands.
You can also get many of those commands compiled for windows and then run them using the command with the full path or only the command if the executable is in a path known by adding the paths to the executable files in Windows by :
1) Running in the terminal: PATH %PATH%;C:\<new_path>
2) Creating command aliases like: doskey np=C:\<new_path>\new_command.exe $*. $* is used to be able to transmit parameters
I am a newbie to UNIX, i want to print tree structure of files in a directory. below image is example in DOS, what will be the command of Unix to achieve same objective
I think you are looking for the "tree" command. If you are having issues running it you might have to find out how to install it on your specific distribution. For ubuntu installs you can find instructions here:
https://askubuntu.com/questions/507588/not-able-to-install-tree-comand-in-ubuntu
Not sure what you mean by "on Unix". What OS are you running, specifically? Tree should be compatible on Unix systems. You may just have to compile it for your particular OS.
This command prints output like the following (on cygwin):
I'm trying to use a Windows computer to SSH into a Mac server, run a program, and transfer the output data back to my Windows. I've been able to successfully do this manually using Putty.
Now, I'm attempting to automate the process using Plink. I've added Plink to my Windows Path, so if I open cmd and type in a command, I can successfully log in and pass commands to the server:
However, I'd like to automate this using R, to streamline the data analysis process. Based on some searching, the internet seems to think that the shell command is best suited to this task. Unfortunately, it doesn't seem to find Plink, though passing commands through shell to the terminal is working:
If I try the same thing but manually setting the path to Plink using shell, no output is returned, but the commands do not seem to run (e.g. TESTFOLDER is not created):
Does anyone have any ideas for why Plink is unavailable when I try to call it from R? Alternately, if there are other ideas for how this could be accomplished in R, that would also be appreciated.
Thanks in advance,
-sam
I came here looking for an answer to this question, so I only have so much to offer, but I think I managed to get PLINK's initial steps to work in R using the shell function...
This is what worked for me:
NOT in R:
Install PLINK and add its location to your PATH.
Download the example files from PLINK's tutorial (http://pngu.mgh.harvard.edu/~purcell/plink/tutorial.shtml) and put them in a folder whose path contains NO spaces (unless you know something I don't, in which case, space it up).
Then, in R:
## Set your working directory as the path to the PLINK program files: ##
setwd("C:/Program Files/plink-1.07-dos")
## Use shell to check that you are now in the right directory: ##
shell("cd")
## At this point, the command "plink" should be at least be recognized
# (though you may get a different error)
shell("plink")
## Open the PLINK example files ##
# FYI mine are in "C:/PLINK/", so replace that accordingly...
shell("plink --file C:\\PLINK\\hapmap1")
## Make a binary PED file ##
# (provide the full path, not just the file name)
shell("plink --file C:\\PLINK\\hapmap1 --make-bed --out C:\\PLINK\\hapmap1")
... and so on.
That's all I've done so far. But with any luck, mirroring the structure and general format of those lines of code should allow you to do what you like with PLINK from within R.
Hope that helps!
PS. The PLINK output should just print in your R console when you run the lines above.
All the best,
- CC.
Just saw Caitlin's response and it reminded me I hadn't ever updated with my solution. My approach was kind of a workaround, rather than solving my specific problem, but it may be useful to others.
After adding Plink to my PATH, I created a batch script in Windows which contained all my Plink commands, then called the batch script from R using the command shell:
So, in R:
shell('BatchScript.bat')
The batch script contained all my commands that I wanted to use in Plink:
:: transfer file to phosphorus
pscp C:\Users\Sam\...\file zipper#144.**.**.208:/home/zipper/
:: open connection to Dolphin using plink
plink -ssh zipper#144.**.**.208 Batch_Script_With_Remote_Machine_Commands.bat
:: transfer output back to local machine
pscp zipper#144.**.**.208:/home/zipper/output/ C:\Users\Sam\..\output\
Hope that helps someone!