Anders Vig

I read the help output rather than the manual, because the help output tells you what this version on this machine accepts. A short flag is one character and often combines, so three short flags in a row means three operations rather than one. A long flag is spelled out and usually takes a value, sometimes with an equals sign and sometimes with a space. A positional argument is neither and its position is part of the contract. Options that take a value differ on whether the value can be omitted to ask for the current setting, which is conventional on some tools and rejected on others. It is worth testing rather than assuming. Destructive operations deserve a separate page each. A tool that overwrites in place, one that deletes recursively without confirmation, and one that acts on a whole matched set will all do what they were asked with no further questions. I list the ones worth knowing about before first use, and the safer form when one exists. Output is worth reading. A tool that writes to a terminal, to standard output and to a file produces different results depending on which, and the difference is where piping something dangerous happens. I keep a page on the conventions that hold across tools, since they are worth learning once rather than per program. Where a tool has a dry run, that is the answer to most of this, and I list which of the common ones have one. Where a tool supports one, a dry run is the answer to most of the caution this page expresses.