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https://github.com/lbartnik/subprocess
https://github.com/lbartnik/subprocess
r subprocess
Last synced: 3 months ago
JSON representation
- Host: GitHub
- URL: https://github.com/lbartnik/subprocess
- Owner: lbartnik
- License: other
- Created: 2016-11-06T00:57:40.000Z (about 8 years ago)
- Default Branch: master
- Last Pushed: 2018-12-18T02:21:10.000Z (almost 6 years ago)
- Last Synced: 2024-06-22T19:41:54.865Z (5 months ago)
- Topics: r, subprocess
- Language: C++
- Size: 247 KB
- Stars: 49
- Watchers: 5
- Forks: 10
- Open Issues: 3
-
Metadata Files:
- Readme: README.md
- License: LICENSE
Awesome Lists containing this project
- jimsghstars - lbartnik/subprocess - (C++)
README
subprocess
==========================
| CRAN version | Travis build status | AppVeyor | Coverage | Downloads |
| :-------------: |:---------------------:|:--------:|:--------:|:---------:|
| [](https://cran.r-project.org/package=subprocess) | [](https://travis-ci.org/lbartnik/subprocess) | [](https://ci.appveyor.com/project/lbartnik/subprocess) | [](https://codecov.io/gh/lbartnik/subprocess)| [](https://cranlogs.r-pkg.org/) |
Run and interact with a child process in R! `subprocess` brings a new
R API to create, control the life cycle and shutdown a child process
in **Linux**, **Windows** and **Mac OS**. Check this out.
## Remote shell example
Here's an example of running a `ssh` client child process. It connects
to a ssh server using public key (thus, no password). Then we list files
in the remote account and finally gracefully shutdown the child process.
Load the `subprocess` package and start a new child process:
```r
library(subprocess)
ssh_path <- '/usr/bin/ssh'
handle <- spawn_process(ssh_path, c('-T', 'test@example'))
```
Here is the description of the child process:
```r
print(handle)
#> Process Handle
#> command : /usr/bin/ssh -T test@example
#> system id : 17659
#> state : running
```
And here is what the child process has sent so far to its output streams:
```r
process_read(handle, PIPE_STDOUT, timeout = TIMEOUT_INFINITE)
#> [1] "Welcome to Ubuntu 16.10 (GNU/Linux 4.8.0-27-generic x86_64)"
#> [2] ""
#> [3] " * Documentation: https://help.ubuntu.com"
#> [4] " * Management: https://landscape.canonical.com"
#> [5] " * Support: https://ubuntu.com/advantage"
#> [6] ""
#> [7] "0 packages can be updated."
#> [8] "0 updates are security updates."
#> [9] ""
process_read(handle, PIPE_STDERR)
#> character(0)
```
Nothing in the standard error output. Good! Now we ask the remote shell
to list files.
```r
process_write(handle, 'ls\n')
#> [1] 3
process_read(handle, PIPE_STDOUT, timeout = TIMEOUT_INFINITE)
#> [1] "Desktop" "Download" "examples.desktop"
#> [4] "Music" "Public" "Video"
process_read(handle, PIPE_STDERR)
#> character(0)
```
The first number in the output is the value returned by `process_write()`
which is the number of characters written to standard input of the
child process. The final `character(0)` is the output read from the
standard error stream.
We are now ready to close the connection by exiting the remote shell:
```r
process_write(handle, 'exit\n')
#> [1] 5
process_read(handle, PIPE_STDOUT, timeout = TIMEOUT_INFINITE)
#> character(0)
process_read(handle, PIPE_STDERR)
#> character(0)
```
The last thing is making sure that the child process is no longer alive:
```r
process_wait(handle, TIMEOUT_INFINITE)
#> [1] 0
process_status(handle)
#> [1] "exited"
```