Some friends cannot install Apple developer tools command line tools，When installing, it will prompt "The software cannot be installed.，Because it is currently unavailable from the software update server"，Let me teach you how to install it manually。 What are command line tools? Command Line Tools is a small standalone package from Apple，Available for macOS，Expanded the terminal with additional functionality。including but not limited to：svn、git、make、GCC、clang、perl、size、strip、strings、libtool、cpp、what、codesign and others...

By default，Mac computers cannot install external software from non-App Store sources。This is because Mac’s new system enables new security mechanisms。So how to solve this problem? This article will introduce how to allow the installation of non-App Store software on Mac。 Open system preferences：Click the Apple icon in the upper left corner of the screen，Then select "System Preferences" in the drop-down menu。 Go to Security & Privacy：In the System Preferences dialog，Select the "Security & Privacy" option。 Unlock settings：In the lower left corner of the Security & Privacy dialog box，Click the lock button。 Enter system password：Enter the system password in the pop-up interface，Then click "Unlock"。 ...