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I just use grep. If i were to wonder what the -s option of the read command did, i'd try these commands in order until i got an answer: info read |grep \\-s man read |grep \\-s help read |grep \\-s In this case only the info command provided a clear answer. This excellent answer gives the details on the different help systems.
There are a handful of exit codes with reserved special meanings: Exit Code Number Meaning 1 Catchall for general errors 2 Misuse of shell builtins (according to Bash documentation) 126 Command invoked cannot execute 127 "command not found" 128+n Fatal error signal "n" 130 Script terminated by Ctrl-C 255* Exit status out of range ...
tl;dr Exit codes are application specific. There are some loose conventions. false and anything successful prefixed with ! (like ! true) in POSIX shells return exit code 1, but a developer can use any exit code between 0 and 255 for whatever they want. Ultimately you have to look at its documentation (in the best case) or the code (in the worst case) to ...
help is a built-in command in the bash shell (and that shell only) that documents some of the builtin commands and keywords of that shell. That's an internal documentation system of that shell. Other shells have their own documentation system (ksh93 has --help and --man options for its builtins, zsh has a run-help helper that extracts information from ...
Any time you're unfamiliar with a command line tool, it's helpful to take a look a the man page. excerpt - man tar SYNOPSIS tar [OPTION...] [FILE]... The synopsis, which most commands will have, shows that a, b, and c would be the files/directories in this example.
It's common that, when using compression tools, the arguments after the flags and the file to be created are the files to include or add to the newly created file. In this case, a, b, and c are the files to include in your newly created file foo.tbz. The same happens when using other tools besides tar, like zip.
These are the files/directories which the tar command should include in the new created foo.tbz tarball. tar flags: -c Create a new tarball -v verbose -j use bzip2 compression -f foo.tbz Use foo.tbz as (here output) file a b c further arguments: file names/directory names which tar should include in the new tarball.
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