DEMO UNIX/Linux,for example,provides the user with a choice of different shells,which may either be configured to launch automatically at login,or which may be changed on the fly.Each of these shells uses a different configuration file of initial settings and commands that are executed upon startup. Different shells provide different functionality,in terms of certain commands that are implemented directly by the shell without launching any external programs.Most provide at least a rudimentary command interpretation structure for use in shell script programming loops,decision constructs,variables,etc
• UNIX/Linux, for example, provides the user with a choice of different shells, which may either be configured to launch automatically at login, or which may be changed on the fly. ( Each of these shells uses a different configuration file of initial settings and commands that are executed upon startup. ) • Different shells provide different functionality, in terms of certain commands that are implemented directly by the shell without launching any external programs. Most provide at least a rudimentary command interpretation structure for use in shell script programming ( loops, decision constructs, variables, etc. )
Terminal 目日☒ Eile Edit ylew Terminal Tabs Help fdo 0.0 0.0 0.0 0.00.00.0 0.000 sdo 0.0 0.2 0.0 0.20.00.0 0.4 00 sdl 0.0 0.00.00.00.00.0 0.0 00 extended device statistics device r/s w/s kr/s kw/s wait actv ，svc_t %w b fdo 0.0 0.00.00.00.00.0 0.0 00 sdo 0.6 0.038.40.00.00.0 8.2 0 0 sdl 0.0 0.00.00.00.00.00.000 (rootepbg-mw64-vm)-(11/pts)-(00:5115-Jun-2007)-(g1oba1) (/var/tmp/systen-contents/scripts)swap -sh total:1.1G allocated+190M reserved 1,3G used,1.6G available (root0pbg-mw64-vm)-(12/pts)-(00:5315-Jun-2007)-(g1oba1) (/var/tmp/systen-contents/scripts)uptine 12:53am up 9 nin(s),3 users,load average:33.29,67.68,36.81 (root@bg-mv64-vm)-(13/pts)-(00:5315-Jun-2007刀-(g1oba1) (/var/tmp/systen-contents/scripts)w 4:07pm up 17 day(s).15:24,3 users,load average:0.09,0.11.8.66 User tty loging idle 3CPU PCPU what root console 15Jun0718days /usr/bin/ssh-agent --/usr/bi n/d root pts/3 15Jun07 18 4 W root pts/4 15Jun0718days (rootipbg-w64-vm)-(14/pts)-(16:0702-Ju1-2007)-(g1oba1) (/var/tmp/systen-contents/scripts)
Graphical User Interface,GUl Generally implemented as a desktop metaphor,with file folders, trash cans,and resource icons.Icons represent some item on the system,and respond accordingly when the icon is activated. First developed in the early 1970's at Xerox PARC research facility. Mac has traditionally provided ONLY the GUl interface.With the advent of OSX(based partially on UNIX )a command line interface has also become available. Because mice and keyboards are impractical for small mobile devices,these normally use a touch-screen interface today,that responds to various patterns of swipes or "gestures
- Graphical User Interface, GUI • Generally implemented as a desktop metaphor, with file folders, trash cans, and resource icons. Icons represent some item on the system, and respond accordingly when the icon is activated. • First developed in the early 1970's at Xerox PARC research facility. • Mac has traditionally provided ONLY the GUI interface. With the advent of OSX ( based partially on UNIX ), a command line interface has also become available. • Because mice and keyboards are impractical for small mobile devices, these normally use a touch- screen interface today, that responds to various patterns of swipes or "gestures
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Choice of interface Most modern systems allow individual users to select their desired interface,and to customize its operation,as well as the ability to switch between different interfaces as needed.System administrators generally determine which interface a user starts with when they first log in. GUl interfaces usually provide an option for a terminal emulator window for entering command-line commands. Command-line commands can also be entered into shell scripts, which can then be run like any other programs
- Choice of interface • Most modern systems allow individual users to select their desired interface, and to customize its operation, as well as the ability to switch between different interfaces as needed. System administrators generally determine which interface a user starts with when they first log in. • GUI interfaces usually provide an option for a terminal emulator window for entering command-line commands. • Command-line commands can also be entered into shell scripts , which can then be run like any other programs