Introduction
What is the shell?
The shell is a program which purpose is to run other programs. The most popular unix shell is Bash, but zsh, csh and tcsh are still often installed on machines.
Anatomy of a command
A command is composed of the program’s name and optionnaly it’s arguments.
There are some special arguments called options or flags which starts
with - or --.
Example:
Special names
There are some special names which can be used in name and place of files and directories.
.current directory..parent directory*all files and directories
Getting help
From the man
Probably the most important unix command is man, which provides a command’s
manual.
Example:
man ls
LS(1) User Commands LS(1)
NAME
ls - list directory contents
SYNOPSIS
ls [OPTION]... [FILE]...
DESCRIPTION
List information about the FILEs (the current directory by default). Sort entries alphabetically if none of -cftuvSUX nor --sort is specified.
Mandatory arguments to long options are mandatory for short options too.
-a, --all
do not ignore entries starting with .
-A, --almost-all
do not list implied . and ..
# [...]
Importantly, you can seach in the manual by typing / followed by the keyword
you’re looking for.
From the --help option
Most unix programs will have a -h/--help option which provides help
in a more of less long format.
Example:
$ ls --help [15:38:21]
Usage: ls [OPTION]... [FILE]...
List information about the FILEs (the current directory by default).
Sort entries alphabetically if none of -cftuvSUX nor --sort is specified.
Mandatory arguments to long options are mandatory for short options too.
-a, --all do not ignore entries starting with .
-A, --almost-all do not list implied . and ..
--author with -l, print the author of each file
-b, --escape print C-style escapes for nongraphic characters
--block-size=SIZE scale sizes by SIZE before printing them; e.g.
# [...]
From the Internet
It’s essential to get into the habit of asking to the Internet. Typing the right keywords in a search engine very often goes a long way, as many problems have been encountered by many users and reported many times. Hence, it is often very fast to get answers to problems, even some that can be quite tricky to solve.