The libraries must be on the server. By default, they are available on Oracle Linux. If libraries are not present, please install through yum with the following command:

sudo yum install <LIBRARY_NAME>

Download the installation files required to install and set up Tesseract. Files are available at <Unzip the file>/THIRD_PARTY_SOFTWARES/Tesseract.

• Copy the downloaded leptonica tarball (leptonica-1.84.1.tar.gz) in server (installation directory). For eample: /scratch.
• Execute below commands sequentially to install leptonica through autoconf.

  Note:

  In line 4, we used sudo make –j4. Here 4 is the number of CPU core. Generally, the user can use sudo make –jn where n is the number of core. It will make the build process much faster.

  Here, the core number is used as 4 to build the software.

  If the processor does not have multiple cores, the user can use normal make command sudo make.

  sudo tar xvf leptonica-1.84.1.tar.gz
  cd leptonica-1.84.1
  sudo ./configure
  sudo make -j4
  sudo make install

• If the installation through Autoconf fails to generate the configure file or has any other error, follow the commands below to build through CMake.

  sudo tar xvf leptonica-1.84.1.tar.gz
  cd leptonica-1.84.1
  sudo mkdir build
  cd build
  sudo cmake ..
  sudo make -j4
  sudo make install

• Configure the Leptonica path so that the Tesseract Leptonica installation can be found.
• Add the leptonica installation directory in library path. Example: /usr/local/lib ,/usr/lib, /usr/lib64 etc.
• Configure the Leptonica header path. Example: /usr/local/include/leptonica.
• Setup the Pkgconfig path and execute the below mentioned commands to set the path.

  export PKG_CONFIG_PATH=$PKG_CONFIG_PATH:/usr/local/lib/pkgconfig/
  export PKG_CONFIG_PATH=$PKG_CONFIG_PATH:/usr/lib64/pkgconfig/
  export LD_LIBRARY_PATH=$LD_LIBRARY_PATH:/usr/lib
  export LD_LIBRARY_PATH=$LD_LIBRARY_PATH:/usr/local/lib
  export LIBLEPT HEADERSDIR=/usr/local/include/leptonica

  Note:

  Sometimes, tesseract still unable to find lept.pc file.
  It gives configuration errors. For example, Leptonica 1.74 or higher is required. In that case, locate the lept.pc file (usually present at /usr/local/lib/pkgconfig/) with the command locate lept.pc and copy the same in /usr/lib64 directory.

  sudo cp /usr/local/lib/pkgconfig/lept.pc /usr/lib64/pkgconfig/

  Similarly, some services might not be able to get Libleptonica shared object files (.so files, ex: liblept.so, libleptonica.so etc.).

  Note:

  .so files are usually present in the server at /usr/local/lib.
• Type whereis libleptonica or locate libleptonica to find the path and copy the .so files in /usr/lib64 path.

  cd /usr/local/lib
  sudo cp -a *liblept* /usr/lib64

• Copy the Tesseract tarball tesseract-5.4.1.tar.gz to the server (installation directory). For example, /scratch.
• Copy the Tesseract trained files eng.traineddata, osd.traineddata to the server.
• Execute below commands sequentially to build and install Tesseract.

  Note:

  /usr/bin is the directory where tesseract binary will be present if you pass prefix=/usr in configure. You can provide the path based on where you want to install.

  sudo tar xvf tesseract 5.4.1.tar.gz
  cd tesseract-5.4.1
  sudo ./autogen.sh
  sudo ./configure --prefix=/usr
  sudo make -j4
  sudo make install

• Copy the traineddata files in tessdata directory.

  If you use prefix=/usr, tessdata directory is present at /usr/share. If you use prefix=/usr/local, tessdata directory is present at /usr/local/share.

  sudo cp osd.traineddata /usr/share/tessdata
  sudo cp eng.traineddata /usr/share/tessdata

• Execute the below commands to set the Tesseract library path.

  export LD_LIBRARY_PATH=$LD_LIBRARY_PATH:/usr/lib
  export LD_LIBRARY_PATH=$LD_LIBRARY_PATH:/usr/local/lib

• Sometimes services are unable to find libtesseract shared object files (.so files) present in system (Usually at /usr/lib). In that case copy the libtesseract files in /usr/lib64.

  cd /usr/lib
  sudo cp -a *libtesseract* /usr/lib64

• Some programs search for the tessdata directory in a different path (usr/share/tesseract/4/tessdata). Copy the existing tessdata directory to the path (either in /usr/share or /usr/local/share based on your installation).

  cd /usr/share
  sudo mkdir tesseract(execute if tesseract directory is not p resent)
  cd tesseract
  sudo mkdir 4
  cd /usr/share
  sudo cpR tessdata /usr/share/tesseract/4

• Run the below command to set tessdata prefix.

  export TESSDATA_PREFIX=/usr/share/tesseract/4/tessdata

  The Tesseract is now installed.

• Verify the version with below command.

  tesseract --version

  It shows the tesseract version (5.4.1), leptonica version (1.84.1) along with other default libraries (libjpeg, libjpeg-turbo, libpng, libtiff, zlib).