Školení: SA-245
Shell Programming for System Administrators
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Podrobnosti:
Prerequisites:
- Use basic UNIX commands, such as rm, cp, man, more, mkdir, ps, and chmod
- Create and edit text files in vi or a text editor
Objectives:
- Use flow control constructs, such as branching and looping
- Customize system-wide shell initialization files
- Use local and environmental variables and shell metacharacters in scripts
- Use the exit status of a command to determine if the command succeeded or failed
- Develop interactive scripts
- Write a script that uses functions
- Write a script that uses a trap to catch a signal
- Access and process command-line arguments passed into a script
- Write sed scripts to perform noninteractive editing tasks
- Write nawk scripts to manipulate individual fields within a record
- Write nawk scripts to write reports based upon an input file
- Perform string manipulation and integer arithmetic on shell variables
- Write real world administration and reporting scripts
- Use regular expressions with the grep, sed, and nawk
- Manipulate text files with grep, sed, and nawk
Topics:
UNIX Shells and Shell Scripts
- Describe the role of shells in the UNIX environment
- Describe the standard shells
- Define the components of a shell script
- Write a simple shell script
Writing and Debugging Scripts
- Start a script with #!
- Put comments in a script
- Change permissions on a script
- Execute a script
- Debug a script
The Shell Environment
- Use Bourne and Korn shell variables
- Assign values to shell variables
- Unset shell and environment variables
- Customize the user environment using the .profile file
- Perform arithmetic operations
- Create and use aliases
- Customize the Bourne and Korn shell environments
- Use the tilde expansion and command substitution features of the Korn shell
Regular Expressions and the grep Command
- Use and describe regular expressions
- Describe the grep command
- Use the grep command to find patterns in a file
- Use the regular expression characters with the grep command
The sed Editor
- Use the sed editor to perform noninteractive editing tasks
- Use regular expression characters with the sed command
The nawk Programming Language
- Use nawk commands from the command line
- Write simple nawk programs to generate data reports from text files
- Write simple nawk programs to generate numeric and text reports from text files
Conditionals
- Use the exit status of a command as conditional control
- Use the "if" statement to test a condition
- Pass values using command-line arguments (positional parameters) into a script
- Create USAGE messages
- Use conditional if, then, elif, else, and fi constructs
- Use exit, let, and test statements ([[ ]], " ")
- Apply the , ||, and ! Boolean logic operators
- Use the case statement
Interactive Scripts
- Use the print and echo commands to display text
- Use the read command to interactively assign data to a shell variable
- Read user input into one or more variables, using one read statement
- Use special characters, with print and echo, to make the displayed text more user friendly
- Create a "here" document
- Use file descriptors to read from and write to multiple files
Loops
- Write scripts that use for, while, and until loops
- Write a script using the select statement
- Describe when to use loops within a script
- Generate argument lists using command, variable, and file-name substitution
The getopt Statement
- Process script options using the getopts statement
Advanced Variables, Parameters, and Argument Lists
- Declare strings, integers, and array variables
- Manipulate string variables
- Change the values of the positional parameters using the set statement within a script
- Use Korn shell arrays
- Set default values for parameters
- Use the Korn shell built-in let, print, set, and typeset statements
Functions
- Create user-defined functions in a shell script
- Create, invoke, and display functions from the command line
- Pass arguments into a function
- Call functions from special (function) files that are saved in one or more function directories
- Describe where functions are available for use