does not check that ghostscript exists when running pdfcrop

[dalupus]

If you try to run knitr with pdfcrop installed but don't have ghostscript you get the error:
!!! Error: Ghostscript exited with error code 127!
from pdfcrop.

If you run pdfcrop in debug mode you find that this simply means it can't find ghostscript.

If pdfcrop has a dependency on ghostscript then it should be checked that it exists before running it and have a warning that it doesn't exist if it doesn't.

[yihui]

Thanks for the report, but I'm afraid this would mean too much responsibility on my side. The pdfcrop homepage has stated anyway that it depends on Ghostscript: http://pdfcrop.sourceforge.net and I have never received a report on this issue before, so I assume it is a rare issue.

[skanskan]

I have the same error when compiling some latex code with pdflatex.

\documentclass[border=3pt, x11names]{standalone}%
\usepackage{pst-node}
\usepackage{auto-pst-pdf}
\begin{document}
\sffamily
\psset{algebraic, yunit = -1, arrows=->, arrowinset=0.12, linecolor=SteelBlue3, fillcolor=SlateGray3!60, nodesepB=1pt}
\begin{pspicture*}
  \foreach \X[count=\I] in {A, B, C, D, E} {\Cnodeput[linecolor=SteelBlue4, fillstyle=solid]{0}(\I, \I){\X}{\X}}
  \foreach \X/\Y in{A/B, B/C, C/D, D/E}{\ncline{\X}{\Y}}
  \ncarc[arcangle=-25]{A}{D}
\end{pspicture*}
\end{document}

[jtbayly]

I don't know if this is a problem, but I'm seeing this error when building a book with bookdown using the default demo book with one additional line:

```{r, echo=FALSE, fig.align='center', out.width='50%'}
    knitr::include_graphics("images/am_I_crazy.png")
    ```

Worth noting that the build doesn't fail so far as I can tell. I just happened to notice that error in the Travis CI log.

[yihui]

@jtbayly That's too little information for us to tell anything. Please read and follow the issue guide exactly to provide all the required information. Thanks!

[jtbayly]

I’m sorry, but I don’t have any idea what versions of things are used in the Travis CI build process (except Pandoc, which is specified in the demo book .travis.yml file as pandoc_version: 1.19.2.1). I also don’t know how to get an xfun session out of the Travis virtual machine.

I’m just reporting it as a courtesy. If you care about it or think it’s worth looking into it, you can build the demo book with Travis CI, after adding a sub-directory with an image and that line above.

Sorry I can’t provide more in this instance without more instruction.

[yihui]

No worries. Could you at least provide a link to the Travis log (or better, your Github repo as a reproducible example)?

Without further information, it's really hard to guess. There was a bug related to this before knitr 1.28, but I have fixed it earlier this year: https://github.com/yihui/knitr/releases/tag/v1.28 If you are using the latest version of knitr, I cannot think of a reason why this problem can still occur.

[jtbayly]

This particular branch seems to build just fine, but has the error in the Travis CI log.

Here's the Travis log.

Perhaps the Travis CI builds aren't using knitr 1.28 yet?

Edit: I managed to figure out how to output the xfun session info into the book, and here's what I got:

## R version 4.0.2 (2020-06-22) Platform: x86_64-pc-linux-gnu (64-bit) Running under: Ubuntu 16.04.6 LTS  Locale:   LC_CTYPE=en_US.UTF-8       LC_NUMERIC=C                 LC_TIME=en_US.UTF-8        LC_COLLATE=en_US.UTF-8       LC_MONETARY=en_US.UTF-8    LC_MESSAGES=en_US.UTF-8      LC_PAPER=en_US.UTF-8       LC_NAME=C                    LC_ADDRESS=C               LC_TELEPHONE=C               LC_MEASUREMENT=en_US.UTF-8 LC_IDENTIFICATION=C         Package version:   evaluate_0.14   glue_1.4.2      graphics_4.0.2  grDevices_4.0.2   highr_0.8       knitr_1.29      magrittr_1.5    markdown_1.1      methods_4.0.2   mime_0.9        stats_4.0.2     stringi_1.4.6     stringr_1.4.0   tools_4.0.2     utils_4.0.2     xfun_0.16         yaml_2.2.1

[yihui]

From https://travis-ci.org/github/warhornmedia/bookdown-test/builds/725242542, the actual error was:

! LaTeX Error: File `../images/am_I_crazy' not found.
Error: LaTeX failed to compile bookdown-demo.tex. See https://yihui.org/tinytex/r/#debugging for debugging tips. See bookdown-demo.log for more info.

That was caused by the fact that the image does not exist.

The ghostscript issue caused a warning:

In addition: Warning message:
In system2("pdfcrop", shQuote(c(x, x)), stdout = if (quiet) FALSE else "") :
  error in running command

This only means figure cropping failed: https://bookdown.org/yihui/rmarkdown-cookbook/crop-plot.html I'm not sure if you really need this feature. If you don't, you can turn it off by setting knitr::opts_chunk$set(crop = NULL).

I'm not sure what's going on with ghostscript on Travis, and I don't have time to debug it. Sorry.
You need to install ghostscript on Travis: https://github.com/warhornmedia/bookdown-test/pull/1

[yihui]

@dalupus I take back what I said in 2015. Looking at the replies above and linked issues, I feel that it is obviously a highly confusing problem to many people. Therefore I just added the check for the existence of ghostscript. I definitely owe you a "thank you" and it's probably not too late five years later :)

[jtbayly]

I’m so sorry I sent the log with the additional error. That is definitely a separate issue that I was working on. I meant to send the data with only the Ghostscript error.

[yihui]

@jtbayly No worries. I think we are all set now. You can either merge https://github.com/warhornmedia/bookdown-test/pull/1 or

remotes::install_github(c('yihui/knitr', 'rstudio/rmarkdown'))

[github-actions]

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