Daily Archives: September 25, 2019

How to check if a variable is set in Bash?

where ${var+x} is a parameter expansion which evaluates to nothing if var is unset, and substitutes the string x otherwise. To check for non-null/non-zero string variable, i.e. if set, use It’s the opposite of -z. I find myself... Read More | Share it now!

差异两个rpms? – linux

尝试使用pkgdiff来查看RPM包之间的差异: 如果比较SRC.RPM,那么该工具也将提取并比较内部tarball(除非定义了-skip-subarchives选项). ... Read More | Share it now!