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

set Options

Table 2.6 lists the options that can be turned on with the set - arg command. All are initially off except where noted. Full Names, where listed, are arguments to set that can be used with set -o. The Full Names braceexpand, histexpand, history, keyword, and onecmd are not available in versions of bash prior to 2.0. Also, in those versions, hashing is switched with -d.

Table B-6. Options to set

Option	Full Name	Meaning
-a	allexport	Export all subsequently defined or modified variables.
-B	braceexpand	The shell performs brace expansion. This is on by default.
-b	notify	Report the status of terminating background jobs immediately.
-C	noclobber	Don’t allow redirection to overwrite existing files.
-e	errexit	Exit the shell when a simple command exits with non-zero status. A simple command is a command not part of a while, until, or if; or part of a && or \|\| list; or a command whose return value is inverted by !.
	emacs	Use emacs-style command-line editing.
-f	noglob	Disable pathname expansion.
-H	histexpand	Enable ! style history substitution. On by default in an interactive shell.
	history	Enable command history. On by default in interactive shells.
-h	hashall	Disable the hashing of commands.
	ignoreeof	Disallow CTRL-D to exit the shell.
-k	keyword	Place keyword arguments in the environment for a command.
-m	monitor	Enable job control (on by default in interactive shells).
-n	noexec	Read commands and check syntax but do not ...