If chmod 444 fido is executed successfully, then permission of fido is
A. -rwxr-xr-x
B. -rwxr--r--
C. -r--r--r--
D. -r-xr-x—x
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The most convenient command or operation to terminate a foreground process (without signal masking) is
A. kill
B. Ctrl+c
C. halt
D. shutdown
About command ‘# mv abc xyz’, which statement is wrong:
A. If abc is a normal file and xyz doesn't exist before, then this command will change the file name abc to xyz.
B. If abc is a normal file and xyz is a directory, this command will move file abc into directory xyz.
C. If abc is a directory and xyz is also a directory, this command will make abc to be the subdirectory of xyz.
D. If abc is a directory and xyz is a normal file, this command will overwrite xyz, i.e. xyz will lost.
File wang.tar.gz in the current directory. The correct tar command to extract this file is:
A. tar zcvf wang.tar.gz
B. tar zxvf wang.tar.gz
C. tar jcvf wang.tar.gz
D. tar jxvf wang.tar.gz
Which technique is used in the command‘ls -l >tmp’
A. Input redirection
B. Output redirection
C. Pipe
D. Batch
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