linux-notes

Getting help

There is a hoarde of documentaion to be found on just about every part of a linux system.

First, manual pages should be available for anything on a system. If you develop software for linux, remember to make a manual. They are divided into sections based on what type of category of they fit. The manuals can be accessed as such:

• man man this is the manual for man, it is a good starting point for beginners because it explains how the sections work
• man <thing> where is the thing you want information on
• man <section> <thing> when you know what section to search
• apropos <subject> where is a what you want information on but you do not know what man page to seek
• man -k <subject> same as apropos
• man -a <thing> cycles through man pages that match . After quitting from one man page, a menu is presented (if more exist) where you can view the next manual, skip the next one, or quit the man viewer.

Info viewer

Any software that is provided by GNU will probably also have a more comprehensive manual. You can access this by running info <command>. The topics are arranged in a directory so if you want to browse to see what is available, info will get you to the top of the directory. Pressing d in any info topic will jump to the directory as well. If you ask info for a command that does not have an info topic, it will serve the man page instead.

Bash and readline:

For help on bash, see man bash or info bash.

By default, the bash shell is in emacs-mode exposing some emacs key bindings for line editing. These bindings can be extended by creating and modifying a user's readline init file. Alternatively, this behavior can be switched to enable vi style key bindings if preferred. For more info, see info bash section 8. Using emacs lingo, C-x is holding down the Ctrl key and pressing x, and M-x is holding down the Meta* key and pressing x. The Meta key is usually labelled Alt, but can also be used by pressing and releasing Escape. Sometimes Alt may not functioni correctly due to the terminal emulator. Yank means paste. Kill means cut.

Cancel:

• C-g abort search

Move command bindings:

• C-a move cursor to beginning of line
• C-e move cursor to end of the line
• C-f move cursor forward one character
• M-f move cursor forward one word*
• C-b move cursor backwards one character
• M-b move cursor backwards one word*

Kill and yank command bindings:

• C-d kill character at cursor point
• M-d delete to the end of the word from the cursor point
• backspace kill the previos character, is actually called delete in emacs terminology
• M-del deletes backwards from the cursor to the beginning of the word
• C-k kill (delete) all text from the point (cursor) to the end of the line
• C-w kill from cursor to previous whitespace
• C-y yank the previosly killed text to cursor point
• M-y rotate the kill ring and yank the new top, only if previous command was C-y or M-y

History commands:

• C-r reverse search, enter a search pattern, you can use the command as-is or move the cursor to make changes
• C-p previous command
• C-n next command
• M-< move to first command in history
• M-> move to last command in history

Undo:

• C-_ or C-x C-u undoes the last edit, especially kill commands (e.g. delete word with M-d) this supposedly can be repeated until there is a blank line left. my results have been mixed.
• C-u clears the line

More:

• C-l clear the terminal screen, same as typing clear

Modifier:

• You can use M-<numerical argument> to alter the above commands. For example, to delete 3 characters from the cursor, M-3 C-d. This can be more than one digit or even a negative number can be passed as an argument by doing M-- <number> <command>.

To edit a command in editor: ^xe

How is this editor identified?

C-\ sends SIGKILL when C-c fails to end a program.

Systemd

Services

Edit a service file systemctl edit <service name>

Timers

To get a list of active timers: systemctl list-timers

Shell