Extra Unix Shell Material: Glossary

man command displays the manual page for a given command.

[OPTION]... means the given command can be followed by one or more optional flags.

Flags specified after ellipsis are still optional but must come after all other flags.

While inside the manual page,use / followed by your pattern to do interactive searching.

SSH is a secure alternative to username/password authorization

SSH keys are generated in public/private pairs. Your public key can be shared with others. The private keys stays on your machine only.

The ‘ssh’ and ‘scp’ utilities are secure alternatives to logging into, and copying files to/from remote machine

Wget is a utility for downloading remote webpages. It includes options to mirror an entire site.

curl is another utility for downloading remote webpages. It defaults to outputting the result on screen, this can be piped to other programs.

rsync is a utility for transferring files. It can use the SSH protocol and is useful for mirroring complicated directory structures from one computer to another.

Correct permissions are critical for the security of a system.

File permissions describe who and what can read, write, modify, and access a file.

Use ls -l to view the permissions for a specific file.

Use chmod to change permissions on a file or directory.

FIXME

When we talk of ‘job control’, we really mean ‘process control’

A running process can be stopped, paused, and/or made to run in the background

A process can be started so as to immediately run in the background

Paused or backgrounded processes can be brought back into the foreground

Process information can be inspected with ps

Aliases are used to create shortcuts or abbreviations

The .bashrc and .bash_profile files allow us to customize our bash environment.

The PS1 system variable can be changed to customize your bash prompt.

Shell variables are by default treated as strings

The PATH variable defines the shell’s search path

Variables are assigned using “=” and recalled using the variable’s name prefixed by “$”

We can substitue variables for the output of commands using the $(command) syntax.

We can loop through sets of values in a “parameter sweep”.

For loops can take a single variable with space separated arguments and treat each as a separate item to iterate over.

Awk is a useful utility for breaking up data into subfields.

Awk can search for certain text to only process certain lines of a file.