在Bash中,似乎有几个变量具有特殊的,一致意义的值.例如,
./myprogram &; echo $!
将返回后台进程的PID myprogram.我知道其他人,比如$?我认为是目前的TTY.还有其他人吗？
我试图在Ubuntu 14.04安装卡桑德拉和我面临的，当我运行这个命令这个问题：sudo apt-get install cassandra。
Reading package lists... Done
Building dependency tree
Reading state information... Done
Package cassandra is not available, but is referred to by another package.
This may mean that the package is missing, has been obsoleted, or is only available from another source
E: Package 'cassandra' has no installation candidate
请帮我修复它。尝试了一些链接，但没有奏效。我需要在我的机器上安装 cassandra