Linux Basics

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PHP's gd library is missing or unable to create PNG images

a @@file@@ is a collection of data with a name (a @@filename@@ to be precise). Although it may be stored in seporate chuncks in different location on the hardware, programs will generaly work with a file as a single contiuous collection of data.

a @@directory@@ is construct for grouping and organizing @@files@@. In UNIX and Linux, @@directories@@ can contain, @@files@@, other @@directories@@, @@links@@ and @@devices@@. You may be use to calling directories @@folders@@ or @@namespaces@@.

a @@path@@ is a way of nameing the location of a file, directory, link or device. @@Pathes@@ can be @@relative@@ or @@absolute@@ and are often used as the prefix to a filename. For example, if I want to list the contents of a directory that is in my home directory called cheese, I can type:
```
ls ~/cheese/
```

a @@link@@ is a filesystem pointer. You may be use to calling a @@link@@ an @@alias@@ or a @@shortcut@@

ls: lists the files in your current working directory for that shell.
- more ways: ls -a, ls -l, ls -la
cd directory : changes the current working directory to directory where directory may be a fully qualified path. A ~ indicates your home directory. ~bob indicates the home directory of bob.
rm filename : removes the file filename where filesname may be a fully qualified path
cp source destination : copies the file source to the file destination where source and destination may be fully qualified paths.
mv source destination : the same as cp, but it moves the source file instead of copying it. mv can also be used to rename a file with mv oldname newmane
chmod #### file or directory : changes the file or directory permissions for letter yourself and other people access your files. see man chmod for more info.

Printing: the lpr command is the basic printing command. in your shell, type: “lpr filename ” to print the file filename to the printer specified in printername or “lpq” to get a list of jobs sent to the printer.
File compression: “gzip filename” will compress the file filename and give it the .gz name extension. “gzip -d filename.gz” or “gunzip filename.gz” will decompress the file and remove the .gz extension.

Shell commands