Difference between libQtCore.so libQtCore.so.4

[William Wilson]

On Linux, after Qt gets built, there are two sets of libraries. For example, libQtCore.so and libQtCore.so.4 with identical number of bytes. What is the difference between these two?

[wysota]

libQtCore.so.4 is a soft link (an "alias") to libQtCore.so. There should (or could) also be libQtCore.so.4.x.y with x.y denoting the version of Qt. Nothing to worry about - that's a standard procedure on Linux and the extra "file" doesn't occupy space on your disk (excluding the inode needed to store the name itself).