Linux FAQ's & Manuals
- Linux Scripts
- Debian Install
- Bash For Beginners
- Bugzilla
- Consultants Guide
- GCC Manual
- Linux Command Line Tools
- Gnu Pascal Coding Standards
- Linux Installation Disk
- Labolatorium Linux(PL)
- Budowa systemu Linux(PL)
- Linux Dictionary
- Network Administrators
- Rescue Disk for Linux
- Red Hat Installation
- Red Hat Customization
- Red Hat Getting Started
- Red Hat Security
- Secure & Optimize
- Slackware Manual
- Suse Support
- Suse FAQ
HowtoForge: "This how-to will guide you through the entire process of setting up a secure website using SSL and digital certificates..."
Linux Tip: Bash Parameters and Parameter Expansions
developerWorks: "In this tip you will learn how to handle parameters and options in your bash scripts and how to use the shell's parameter expansions to check or modify parameters..."
Kubuntu-Based Stagecoach Rides Into Town
DesktopLinux: "Technalign on May 16 released the final version of Pioneer Stagecoach, a combined workstation and server Linux distribution based on Kubuntu..."
Google Keeps Close Eye on Open Source
eWeek: "DiBona spoke... about a series of issues such as Microsoft's recent saber rattling over patents, Google's open-source development contributions and what GPLv3 means for Google..."
Open Source BI Vendors Get Busy
Computer Business Review: "Open source vendors Pentaho and JasperSoft have rolled out new business intelligence products that look more and more like their commercial-grade enterprise BI counterparts in terms of functionality and licensing..."
4.1. regular expressions
4.1.1. what are regular expressions?
a regular expression is a pattern that describes a set of strings. regular expressions are constructed analogously to arithmetic expressions by using various operators to combine smaller expressions.
the fundamental building blocks are the regular expressions that match a single character. most characters, including all letters and digits, are regular expressions that match themselves. any metacharacter with special meaning may be quoted by preceding it with a backslash.
4.1.2. regular expression metacharacters
a regular expression may be followed by one of several repetition operators (metacharacters):
table 4-1. regular expression operators
| operator | effect |
|---|---|
| . | matches any single character. |
| ? | the preceding item is optional and will be matched, at most, once. |
| * | the preceding item will be matched zero or more times. |
| + | the preceding item will be matched one or more times. |
| {n} | the preceding item is matched exactly n times. |
| {n,} | the preceding item is matched n or more times. |
| {n,m} | the preceding item is matched at least n times, but not more than m times. |
| - | represents the range if it's not first or last in a list or the ending point of a range in a list. |
| ^ | matches the empty string at the beginning of a line; also represents the characters not in the range of a list. |
| $ | matches the empty string at the end of a line. |
| \b | matches the empty string at the edge of a word. |
| \b | matches the empty string provided it's not at the edge of a word. |
| \< | match the empty string at the beginning of word. |
| \> | match the empty string at the end of word. |
two regular expressions may be concatenated; the resulting regular expression matches any string formed by concatenating two substrings that respectively match the concatenated subexpressions.
two regular expressions may be joined by the infix operator "|"; the resulting regular expression matches any string matching either subexpression.
repetition takes precedence over concatenation, which in turn takes precedence over alternation. a whole subexpression may be enclosed in parentheses to override these precedence rules.
4.1.3. basic versus extended regular expressions
in basic regular expressions the metacharacters "?", "+", "{", "|", "(", and ")" lose their special meaning; instead use the backslashed versions "\?", "\+", "\{", "\|", "\(", and "\)".
check in your system documentation whether commands using regular expressions support extended expressions.