Use -j $(nproc) rather than -j4

Compile-from-source-in-Linux.md

@@ -157,7 +157,7 @@ cd libairspy
 git reset --hard v1.0.10
 mkdir build; cd build
 cmake -Wno-dev -DCMAKE_INSTALL_PREFIX=/opt/install/libairspy ..
-make -j4 install
+make -j $(nproc) install
 </code></pre>
 
 <h3>SDRplay RSP1</h3>
@@ -167,7 +167,7 @@ git clone https://github.com/f4exb/libmirisdr-4.git
 cd libmirisdr-4
 mkdir build; cd build
 cmake -Wno-dev -DCMAKE_INSTALL_PREFIX=/opt/install/libmirisdr ..
-make -j4 install
+make -j $(nproc) install
 </code></pre>
 
 <h3>RTL-SDR</h3>
@@ -178,7 +178,7 @@ cd librtlsdr
 git reset --hard be1d1206bfb6e6c41f7d91b20b77e20f929fa6a7
 mkdir build; cd build
 cmake -Wno-dev -DDETACH_KERNEL_DRIVER=ON -DCMAKE_INSTALL_PREFIX=/opt/install/librtlsdr ..
-make -j4 install
+make -j $(nproc) install
 </code></pre>
 
 <h3>Pluto SDR</h3>
@@ -189,7 +189,7 @@ cd libiio
 git reset --hard v0.21
 mkdir build; cd build
 cmake -Wno-dev -DCMAKE_INSTALL_PREFIX=/opt/install/libiio -DINSTALL_UDEV_RULE=OFF ..
-make -j4 install
+make -j $(nproc) install
 </code></pre>
 
 You will need firmware 0.29 or above.
@@ -202,7 +202,7 @@ cd bladeRF/host
 git reset --hard "2019.07"
 mkdir build; cd build
 cmake -Wno-dev -DCMAKE_INSTALL_PREFIX=/opt/install/libbladeRF -DINSTALL_UDEV_RULES=OFF ..
-make -j4 install
+make -j $(nproc) install
 </code></pre>
 
 <h3>HackRF</h3>
@@ -213,7 +213,7 @@ cd hackrf/host
 git reset --hard "v2018.01.1"
 mkdir build; cd build
 cmake -Wno-dev -DCMAKE_INSTALL_PREFIX=/opt/install/libhackrf -DINSTALL_UDEV_RULES=OFF ..
-make -j4 install
+make -j $(nproc) install
 </code></pre>
 
 <h3>LimeSDR</h3>
@@ -224,7 +224,7 @@ cd LimeSuite
 git reset --hard "v20.01.0"
 mkdir builddir; cd builddir
 cmake -Wno-dev -DCMAKE_INSTALL_PREFIX=/opt/install/LimeSuite ..
-make -j4 install
+make -j $(nproc) install
 </code></pre>
 
 <h3>AirspyHF</h3>
@@ -235,7 +235,7 @@ cd airspyhf
 git reset --hard "1.1.5"
 mkdir build; cd build
 cmake -Wno-dev -DCMAKE_INSTALL_PREFIX=/opt/install/libairspyhf ..
-make -j4 install
+make -j $(nproc) install
 </code></pre>
 
 <h3>Perseus</h3>
@@ -247,7 +247,7 @@ git checkout fixes
 git reset --hard afefa23e3140ac79d845acb68cf0beeb86d09028
 mkdir build; cd build
 cmake -Wno-dev -DCMAKE_INSTALL_PREFIX=/opt/install/libperseus ..
-make
+make -j $(nproc)
 make install
 </code></pre>
 
@@ -263,7 +263,7 @@ git checkout v4.0.0.0
 mkdir build
 cd build
 cmake -DCMAKE_INSTALL_PREFIX=/opt/install/uhd ../
-make 
+make -j $(nproc)
 make install
 /opt/install/uhd/lib/uhd/utils/uhd_images_downloader.py
 # The following aren't required if installed to /
@@ -294,7 +294,7 @@ git submodule update
 cd sources
 mkdir build; cd build
 cmake -Wno-dev -DCMAKE_INSTALL_PREFIX=/opt/install/xtrx-images -DENABLE_SOAPY=NO ..
-make
+make -j $(nproc)
 make install
 </code></pre>
 
@@ -312,7 +312,7 @@ cd SoapySDR
 git reset --hard "soapy-sdr-0.7.1"
 mkdir build; cd build
 cmake -DCMAKE_INSTALL_PREFIX=/opt/install/SoapySDR ..
-make -j4 install
+make -j $(nproc) install
 </code></pre>
 
 So far so good but we will need the support libraries that are the pieces (plugins) that make the link between SoapySDR and the libraries that drive the hardware. They have to be compiled one by one separately as you need them. Let's take a simple example for RTL-SDR assuming that librtlsdr has been compiled and installed as described earlier in <code>/opt/install/librtlsdr</code>:
@@ -324,7 +324,7 @@ git clone https://github.com/pothosware/SoapyRTLSDR.git
 cd SoapyRTLSDR
 mkdir build; cd build
 cmake -DCMAKE_INSTALL_PREFIX=/opt/install/SoapySDR  -DRTLSDR_INCLUDE_DIR=/opt/install/librtlsdr/include -DRTLSDR_LIBRARY=/opt/install/librtlsdr/lib/librtlsdr.so -DSOAPY_SDR_INCLUDE_DIR=/opt/install/SoapySDR/include -DSOAPY_SDR_LIBRARY=/opt/install/SoapySDR/lib/libSoapySDR.so ..
-make -j4 install
+make -j $(nproc) install
 </pre></code>
 
 The support libraries are installed in <code>/opt/install/SoapySDR/lib/SoapySDR/modules0.7</code> (for the 0.7 version). 
@@ -336,7 +336,7 @@ git clone https://github.com/pothosware/SoapyHackRF.git
 cd SoapyHackRF
 mkdir build; cd build
 cmake -DCMAKE_INSTALL_PREFIX=/opt/install/SoapySDR -DLIBHACKRF_INCLUDE_DIR=/opt/install/libhackrf/include/libhackrf -DLIBHACKRF_LIBRARY=/opt/install/libhackrf/lib/libhackrf.so -DSOAPY_SDR_INCLUDE_DIR=/opt/install/SoapySDR/include -DSOAPY_SDR_LIBRARY=/opt/install/SoapySDR/lib/libSoapySDR.so ..
-make -j4 install
+make -j $(nproc) install
 </code></pre>
 
 <h4>LimeSDR</h4>
@@ -346,7 +346,7 @@ Assuming you already have cloned LimeSuite and build it in the corresponding pre
 <pre><code>cd /opt/build
 cd LimeSuite/builddir
 cmake -Wno-dev -DCMAKE_INSTALL_PREFIX=/opt/install/LimeSuite -DCMAKE_PREFIX_PATH=/opt/install/SoapySDR ..
-make -j4 install
+make -j $(nproc) install
 cp /opt/install/LimeSuite/lib/SoapySDR/modules0.7/libLMS7Support.so /opt/install/SoapySDR/lib/SoapySDR/modules0.7
 </code></pre>
 
@@ -359,7 +359,7 @@ cd SoapyRemote
 git reset --hard "soapy-remote-0.5.1"
 mkdir build; cd build
 cmake -DCMAKE_INSTALL_PREFIX=/opt/install/SoapySDR -DSOAPY_SDR_INCLUDE_DIR=/opt/install/SoapySDR/include -DSOAPY_SDR_LIBRARY=/opt/install/SoapySDR/lib/libSoapySDR.so ..
-make -j4 install
+make -j $(nproc) install
 </code></pre>
 
 <h3>Build SDRangel</h3>
@@ -400,7 +400,7 @@ cmake -Wno-dev -DDEBUG_OUTPUT=ON -DRX_SAMPLE_24BIT=ON \
 -DLIBSIGMF_DIR=/opt/install/libsigmf \
 -DDAB_DIR=/opt/install/libdab \
 -DCMAKE_INSTALL_PREFIX=/opt/install/sdrangel ..
-make -j4 install
+make -j $(nproc) install
 </code></pre>
 
 <h2>Developer Docs</h2>