book

Learning the bash Shell, Second Edition

by Cameron Newham, Bill Rosenblatt

January 1998

Beginner

336 pages

10h 6m

English

O'Reilly Media, Inc.

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bash Versions

What Is a Shell?
The Bourne Again ShellFeatures of bash
Commands, Arguments, and Options
DirectoriesThe working directoryTilde notationChanging working directoriesFilenames, Wildcards, and Pathname ExpansionBrace Expansion
Standard I/OI/O RedirectionPipelines
Background I/OBackground Jobs and Priorities
QuotingBackslash-EscapingQuoting Quotation MarksContinuing LinesControl Keys
Enabling Command-Line Editing
Basic CommandsWord CommandsLine CommandsMoving Around in the History FileTextual CompletionMiscellaneous Commands
Simple Control Mode CommandsEntering and Changing TextDeletion CommandsMoving Around in the History FileCharacter-Finding CommandsTextual CompletionMiscellaneous Commands
The readline Startup Filereadline variablesKey Bindings Using bind
The .bash_profile, .bash_logout, and .bashrc Files
shopt
Variables and QuotingBuilt-In VariablesEditing mode variablesMail variablesPrompting variablesCommand search pathCommand hashingDirectory search path and variablesMiscellaneous variables
Environment VariablesTerminal typesOther common variablesThe Environment File
Shell Scripts and FunctionsFunctions
Positional ParametersPositional parameters in functionsLocal Variables in FunctionsQuoting with $@ and $*More on Variable Syntax
Syntax of String OperatorsPatterns and Pattern MatchingLength Operator
if/elseExit Status and ReturnReturnCombinations of Exit StatusesCondition TestsString comparisonsFile attribute checkingInteger Conditionals
Command-Line OptionsshiftOptions with Argumentsgetopts
Arithmetic ConditionalsArithmetic Variables and Assignment
I/O RedirectorsHere-documentsFile Descriptors
echoOptions to echoecho escape sequencesreadReading lines from filesI/O redirection and multiple commandsCommand blocksReading user input
Quotingcommand, builtin, and enableeval
Process IDs and Job Numbers
Foreground and BackgroundSuspending a Job
Control-Key SignalskillpsSystem VBSD
Traps and FunctionsProcess ID Variables and Temporary FilesIgnoring SignalsdisownResetting Traps
waitAdvantages and Disadvantages of CoroutinesParallelization
Subshell InheritanceNested Subshells
Basic Debugging AidsSet OptionsFake SignalsEXITDEBUG
Structure of the DebuggerThe driver scriptexecThe PreambleDebugger FunctionsCommandsSteppingBreakpointsBreak conditionsExecution tracingDebugger limitationsA Sample bashdb SessionExercises
Installing bash as the Standard ShellPOSIX ModeCommand-Line Options
umaskulimitTypes of Global Customization
Restricted ShellA System Break-In ScenarioPrivileged Mode
Obtaining bash
DocumentationConfiguring and Building bashTesting bashPotential ProblemsInstalling bash as a Login ShellExamples
Asking QuestionsReporting Bugs
The Bourne Shell
Invocation
Reserved Words
FTP

Content preview from Learning the bash Shell, Second Edition

emacs Editing Mode

If you are an emacs user, you will find it most useful to think of emacs editing mode as a simplified emacs with a single, one-line window. All of the basic commands are available for cursor motion, cut-and-paste, and search.

Basic Commands

emacs-mode uses control keys for the most basic editing functions. If you aren’t familiar with emacs, you can think of these as extensions of the rudimentary “erase” character (usually BACKSPACE or DEL) that UNIX provides through its interface to users’ terminals. For the sake of consistency, we’ll assume your erase character is DEL from now on; if it is CTRL-H or something else, you will need to make a mental substitution. The most basic control-key commands are shown in Table 2.1. (Important: remember that typing CTRL-D when your command line is empty may log you off!) The basic keyboard habits of emacs-mode are easy to learn, but they do require that you assimilate a couple of concepts that are peculiar to the emacs editor.

Table 2-1. Basic emacs-Mode Commands

Command	Description
CTRL-B	Move backward one character (without deleting)
CTRL-F	Move forward one character
DEL	Delete one character backward
CTRL-D	Delete one character forward

The first of these is the use of CTRL-B and CTRL-F for backward and forward cursor motion. These keys have the advantage of being obvious mnemonics. You can also use the left and right cursor motion keys (“arrow” keys), but for the rest of this discussion we will use the control keys, as ...