#18: Search file(s) for lines that match an extended expression (extended grep)
#21: .bz2 application/x-bzip2bzip2Unix-likeAnopen source,patent- androyalty-free compression format. The compression algorithm is aBurrows-Wheeler transformfollowed by amove-to-front transformand finallyHuffman coding
gz - GNUZip, the primary compression format used byUnix-likesystems. The compression algorithm
.tar - A common archive format used on Unix-like systems. Generally used in conjunction with compressors such asgzip,bzip2,compressorxzto create .tar.gz, .tar.bz2, .tar.Z or tar.xz files.
#23: halt,poweroff, andrebootare commands you can run asrootto stop the system hardware.
haltinstructs the hardware to stop all CPU functions.
poweroffsends anACPIsignal which instructs the system to power down.
rebootinstructs the system toreboot.