这是我的gs命令，而不是合并2页的一页pdf文件：
gs -dNOPAUSE -dSAFER -sDEVICE=pdfwrite -sOUTPUTFILE=/tmp/blahblahblah.pdf -dBATCH page1.pdf page2.pdf
这是输出：
GPL Ghostscript 8.70 (2009-07-31)
Copyright (C) 2009 Artifex Software, Inc. All rights reserved.
This software comes with NO WARRANTY: see the file PUBLIC for details.
Processing pages 1 through 1.
Page 1
Processing pages 1 through 1.
Page 1
Can't find (or can't open) font file /usr/share/ghostscript/8.70/Resource/Font/ArialMT.
Can't find (or can't open) font file ArialMT.
Can't find (or can't open) font file /usr/share/ghostscript/8.70/Resource/Font/ArialMT.
Can't find (or can't open) font file ArialMT.
Querying operating system for font files...
Can't find (or can't open) font file /usr/share/ghostscript/8.70/Resource/Font/ArialMT.
Can't find (or can't open) font file ArialMT.
Didn't find this font on the system!
Substituting font Helvetica for ArialMT.
Loading NimbusSanL-Regu font from /usr/share/fonts/default/Type1/n019003l.pfb... 3397696 1943901 17192756 15861178 3 done.
找不到字体ArialMT，Helvetica替换为scp。我通过identify -format %n '/tmp/blahblahblah.pdf'
从服务器获取合并文件，并在我的本地系统中打开它。该文件已正确合并，包括2页。所以文件没有问题。现在我使用下面的命令来获取PDF页面数：
identify: Postscript delegate failed `/tmp/blahblahblah.pdf': No such file or directory @ error/pdf.c/ReadPDFImage/664.
此命令无法获取页数并给出以下错误：
/tmp/blahblahblah.pdf NB：我应该注意identify路径中存在该文件！
为什么我无法通过def create
# Here!!!!
@goal = current_user.goals.new(goal_params)
@goal.save
redirect_to root_path, notice: "Objectif sauvegardé"
end
获取页数？
示例文件附在以下链接中：
2 PDF sample file