Libtool library used but `LIBTOOL' is undefined?

I came across the same issue when install geoip for nginx in centos (when trying to run make command) and this is what I have done. yum install libtool Added below line at the end of configure.in AC_CONFIG_MACRO_DIR([m4])

Add below line at the end of Makefile.am ACLOCAL_AMFLAGS = -I m4

run $ aclocal $ libtoolize

Don't ask me why. But this worked.

I had the same issue. Did the following

$brew install libtool
==> Downloading https://downloads.sf.net/project/machomebrew/Bottles/libtool-    2.4.2.mavericks.bottle.2.tar.gz
######################################################################## 100.0%
==> Pouring libtool-2.4.2.mavericks.bottle.2.tar.gz
==> Caveats
In order to prevent conflicts with Apple's own libtool we have prepended a "g"
so, you have instead: glibtool and glibtoolize.
==> Summary
🍺  /usr/local/Cellar/libtool/2.4.2: 66 files, 2.2M
fdk-aac $ glibtoolize
fdk-aac $ autoreconf -fiv
fdk-aac $ ./configure
fdk-aac $ make
fdk-aac $ make -install
go to ffmpeg/build
ffmpeg/build$ ../configure --enable-libfdk-aac --enable-nonfree
ffmpeg/build$make
ffmpeg/build$sudo make install
do ls /usr/local/lib/*fdk* check that libfdk-aac is installed
go to my application

 myapp/build$cmake ../
 myapp/build$make

Hope this helps

The error is telling you that either libtool is not installed, or that you are not checking for it in configure.ac. Add the line LT_INIT in configure.ac. If autoreconf then complains that it doesn't know what LT_INIT is, you should either install libtool, upgrade your installation of libtool or use the deprecated AC_PROG_LIBTOOL in configure.ac. (AC_PROG_LIBTOOL should be replaced by LT_INIT in newer projects.)