Add apt.txt

README.md

@@ -1,5 +1,19 @@
 # Minimal Example of Tutorial in Quarto with R and System Requirements
 
-[index.qmd](index.qmd) show all the **required** metadata used by Methods Hub.
+[`index.qmd`](index.qmd) show all the **required** metadata used by Methods Hub.
 
-This repository uses [install.R](install.R) as [configuration file](https://mybinder.readthedocs.io/en/latest/using/config_files.html).
+This repository uses [`install.R`](install.R) and [`apt.txt`](apt.txt) as [configuration file](https://mybinder.readthedocs.io/en/latest/using/config_files.html).
+[`apt.txt`](apt.txt) is required because of the system requirements of the [units R package](https://cran.r-project.org/web/packages/units/index.html).
+Without the [`apt.txt`](apt.txt), the rendering of [`index.qmd`](index.qmd) will raise a error similar to
+
+```
+Quitting from lines 31-38 (index.qmd) 
+Error: package or namespace load failed for 'units' in dyn.load(file, DLLpath = DLLpath, ...):
+ unable to load shared object '/srv/rlibs/units/libs/units.so':
+  libudunits2.so.0: cannot open shared object file: No such file or directory
+In addition: Warning message:
+In do_once((if (is_R_CMD_check()) stop else warning)("The function xfun::isFALSE() will be deprecated in the future. Please ",  :
+  The function xfun::isFALSE() will be deprecated in the future. Please consider using base::isFALSE(x) or identical(x, FALSE) instead.
+
+Execution halted
+```

apt.txt

@@ -0,0 +1 @@
+libudunits2-dev

index.qmd

@@ -19,13 +19,19 @@ plot(rnorm(10), rnorm(10))
 
 ## Dependencies
 
-Packages that need to be installed for the reader should be listed in the `install.R` file. For example, with
+Packages that need to be installed for the reader should be listed in the `install.R` file. For example,
 
 ```r
 install.packages("units")
 ```
 
-in the `install.R` file, is possible to execute
+R packages with system requirements, must have the system requirements installed using the `apt.txt`. For example,
+
+```
+libudunits2-dev
+```
+
+With the R package in the `install.R` file and the system requirements in the `apt.txt` file, is possible to execute
 
 ```{r}
 library(units)