Which of the following is not true about Twitter?
A) Users do not have "friends" on Twitter.
B) Users can post a link to another user's account by using the # sign.
C) Users have the option to post a tweet they like to their followers, which is known as retweeting.
D) The core of the communication is by "following" other people's accounts.
B
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User interfaces include all except:
A) natural-language interfaces. B) indirect manipulation interface. C) question-and-answer interfaces. D) menu interfaces. E) form-fill interface.
Goal Seek can be set to minimize the objective cell
Indicate whether the statement is true or false
What do you think would happen to file2hard if you opened a text editor and changed the text in file2new.txt?
Symbolic Links and other Special File Types You have now seen some of the different file types in Linux. The first character in each file listing in an ls –l command shows the file type. The three different types of files in Linux including their sub-types and characters are: ? Regular files (-) including: ? Readable files – text files ? Binary files - programs ? Image files ? Compressed files ? Directory files (d) ? Folders ? Special Files including: ? Block files (b) – Files used to access physical hardware like mount points to access hard drives. ? Character device files (c) – Files that provide a serial stream of input and output. tty terminals are examples of this type of file. ? Pipe files (p) – A file used to pass information where the first bytes in are the first bytes. This is also known as FIFO (first in first out). ? Symbolic Link files (l) – Files used to link to other files or directories. There are two types: symbolic links and hard links. ? Socket files (s) – These are used to pass information from application to application in order to communicate over a network. Step 1. Examine file types. a. Use the ls -l command to display the files. Notice the first characters of each line are either a “–” indicating a file or a “d” indicating a directory
[analyst@secOps ~]$ ls -l total 28 drwxr-xr-x 3 analyst analyst 4096 Aug 16 15:15 cyops_folder2 drwxr-xr-x 2 analyst analyst 4096 Sep 26 2014 Desktop drwx------ 3 analyst analyst 4096 Jul 14 11:28 Downloads drwxr-xr-x 8 analyst analyst 4096 Jul 25 16:27 lab.support.files drwxr-xr-x 3 analyst analyst 4096 Mar 3 18:23 second_drive -rw-r--r-- 1 analyst analyst 142 Aug 16 15:11 some_text_file.txt -rw-r--r-- 1 analyst analyst 254 Aug 16 13:38 space.txtb. Produce a listing of the /dev directory. Scroll to the middle of the output and notice how the block files begin with a “b”, the character device files begin with a “c” and the symbolic link files begin with an “l”:
[analyst@secOps ~]$ ls -l /dev/c. Symbolic links in Linux are like shortcuts in Windows. There are two types of links in Linux: symbolic links and hard links. The difference between symbolic links and hard links is that a symbolic link file points to the name of another file and a hard link file points to the contents of another file. Create two files by using echo:
[analyst@secOps ~]$ echo "symbolic" > file1.txt [analyst@secOps ~]$ cat file1.txt symbolic [analyst@secOps ~]$ echo "hard" > file2.txt [analyst@secOps ~]$ cat file2.txt hardd. Use ln –s to create a symbolic link to file1.txt, and ln to create a hard link to file2.txt:
[analyst@secOps ~]$ ln –s file1.txt file1symbolic [analyst@secOps ~]$ ln file2.txt file2harde. Use the ls –l command and examine the directory listing:
[analyst@secOps ~]$ ls -l total 40 drwxr-xr-x 3 analyst analyst 4096 Aug 16 15:15 cyops_folder2 drwxr-xr-x 2 analyst analyst 4096 Sep 26 2014 Desktop drwx------ 3 analyst analyst 4096 Jul 14 11:28 Downloads lrwxrwxrwx 1 analyst analyst 9 Aug 17 16:43 file1symbolic -> file1.txt -rw-r--r-- 1 analyst analyst 9 Aug 17 16:41 file1.txt -rw-r--r-- 2 analyst analyst 5 Aug 17 16:42 file2hard -rw-r--r-- 2 analyst analyst 5 Aug 17 16:42 file2.txt drwxr-xr-x 8 analyst analyst 4096 Jul 25 16:27 lab.support.files drwxr-xr-x 3 analyst analyst 4096 Mar 3 18:23 second_drive -rw-r--r-- 1 analyst analyst 142 Aug 16 15:11 some_text_file.txt -rw-r--r-- 1 analyst analyst 254 Aug 16 13:38 space.txtNotice how the file file1symbolic is a symbolic link with an l at the beginning of the line and a pointer -> to file1.txt. The file2hard appears to be a regular file, because in fact it is a regular file that happens to point to the same inode on the hard disk drive as file2.txt. In other words, file2hard points to the same attributes and disk block location as file2.txt. f. Change the names of the original files: file1.txt and file2.txt, and notice how it affects the linked files.
[analyst@secOps ~]$ mv file1.txt file1new.txt [analyst@secOps ~]$ mv file2.txt file2new.txt [analyst@secOps ~]$ cat file1symbolic cat: file1symbolic: no such file or directory [analyst@secOps ~]$ cat file2hard hardNotice how file1symbolic is now a broken symbolic link because the name of the file that it pointed to file1.txt has changed, but the hard link file file2hard still works correctly because it points to the inode of file2.txt and not its name which is now file-2new.txt.
Input into B1 a number:2 Input into B2 a text:books Input into B3 a formula:= "You have "&B1&B2 What EXACTLY is the result in B3:
A. None of the others. B. You have books C. You have 2books D. You have 2 books