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This module provide basics of using the Linux command line. After studying this chapter you should be able to: Understanding the basic shell; working with formatting commands and options, learn the effects of variables, globbing and quoting.
Module Command Line Skills This slide deck is for LPI Academy instructors to use for lectures for LPI Academy courses ©Copyright Network Development Group 2013 Exam Objective 2.1 Basics of using the Linux command line Objective Summary – Understanding the basic shell – Working with formatting commands and options – Learn the effects of variables, globbing and quoting This slide deck is for LPI Academy instructors to use for lectures for LPI Academy courses ©Copyright Network Development Group 2013 CLI or Basic Shell This slide deck is for LPI Academy instructors to use for lectures for LPI Academy courses ©Copyright Network Development Group 2013 The Command Line Interface • • Text based interface Access via a Terminal – – • • GUI-based terminals Virtual terminals Commands passed to a shell Shell prompt: [sysadmin@localhost ~] This slide deck is for LPI Academy instructors to use for lectures for LPI Academy courses âCopyright Network Development Group 2013 Shell Features • • Command history – ability to re-execute previous commands quickly Scripting – create programs by placing shell commands in a file to run Alias – create shortcuts to longer commands Variables – store information that can be used to modify the functionality of the shell or commands This slide deck is for LPI Academy instructors to use for lectures for LPI Academy courses ©Copyright Network Development Group 2013 Understanding Command Structure This slide deck is for LPI Academy instructors to use for lectures for LPI Academy courses ©Copyright Network Development Group 2013 Command format • Basic format: – • • command [options] [arguments] Options change the behavior of command Arguments are used to provide additional information for a command This slide deck is for LPI Academy instructors to use for lectures for LPI Academy courses ©Copyright Network Development Group 2013 Command options • Vary based on command • Older option format: -a – • Can be combined: -abc = -a -b -c Newer (GNU) option format: all This slide deck is for LPI Academy instructors to use for lectures for LPI Academy courses ©Copyright Network Development Group 2013 Command History • • • • View previous commands: history Bring up previous commands: up arrow Modify previous commands: left arrow, right arrow, etc Execute a previous command: ! This slide deck is for LPI Academy instructors to use for lectures for LPI Academy courses ©Copyright Network Development Group 2013 Variables This slide deck is for LPI Academy instructors to use for lectures for LPI Academy courses ©Copyright Network Development Group 2013 Shell Variables • • Used to store system information View with echo command: echo $HISTSIZE • Modify: HISTSIZE = 500 • Changes are temporary • Place commands in ~/.bashrc to make permanent This slide deck is for LPI Academy instructors to use for lectures for LPI Academy courses ©Copyright Network Development Group 2013 PATH Variable • • • Determines where commands are executed from May need to be modified for custom software Example: This slide deck is for LPI Academy instructors to use for lectures for LPI Academy courses ©Copyright Network Development Group 2013 Command Path and Aliases This slide deck is for LPI Academy instructors to use for lectures for LPI Academy courses ©Copyright Network Development Group 2013 Find command location • • Hard to determine where a command is located Instead of searching directories in the PATH variable manually, use the which command: – – which cal which date This slide deck is for LPI Academy instructors to use for lectures for LPI Academy courses ©Copyright Network Development Group 2013 Aliases • • • • • Used to make shortcuts for longer commands View aliases: alias Create alias: alias name=command Change are temporary To make permanent, place alias command in ~/.bashrc file This slide deck is for LPI Academy instructors to use for lectures for LPI Academy courses ©Copyright Network Development Group 2013 Additional Command Structure This slide deck is for LPI Academy instructors to use for lectures for LPI Academy courses ©Copyright Network Development Group 2013 Globbing • • • • Used to match sets of files in a directory * = match zero or more of any characters ? = match exactly one of any character [ ] = match exactly one of a set of characters: – – echo [abc]*.txt echo [!abc]*.txt This slide deck is for LPI Academy instructors to use for lectures for LPI Academy courses ©Copyright Network Development Group 2013 Quoting • • Double quotes – used to disable the meaning of some metacharacters, like glob characters Single quotes – used to disable the meaning of all metacharacters – • Can use \ to disable next character only Backquotes – used to execute a command within another command line This slide deck is for LPI Academy instructors to use for lectures for LPI Academy courses ©Copyright Network Development Group 2013 Control Statements • • • The ; character - Used to separate commands on a command line The && characters – Used to execute the second command if the first command succeeds The || characters – Used to execute the second command if the first command fails This slide deck is for LPI Academy instructors to use for lectures for LPI Academy courses ©Copyright Network Development Group 2013 ... courses ©Copyright Network Development Group 2013 Command options • Vary based on command • Older option format: -a – • Can be combined: -abc = -a -b -c Newer (GNU) option format: all This slide... character - Used to separate commands on a command line The && characters – Used to execute the second command if the first command succeeds The || characters – Used to execute the second command. .. Group 2013 Command History • • • • View previous commands: history Bring up previous commands: up arrow Modify previous commands: left arrow, right arrow, etc Execute a previous command: !