程序代写代做代考 file system Basic Unix Operations on Files and Directories
Basic Unix Operations on Files and Directories
Basic Unix Operations on Files and Directories
Prof. Susan Older
17 January 2017
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Unix Beginnings (1969 at Bell Labs)
Design philosophy:
View everything as a file (but with different types).
Incorporate lots of small commands that can be combined easily to
accomplish more complex tasks.
Employ a hierarchical file system, which forms a tree structure:
/
bin/ usr/ Users/
make bin/ lib/ joule/ sueo/
plans/ toys treats
training.pdf walks.txt
zip zsh/
Note: / is called the root directory.
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Current Working Directory and Pathnames
When you log in (or start a Terminal window), your current working
directory is your home directory:
/Users/joule is my dog Joule’s home directory.
~ is abbreviation for one’s home directory.
. is abbreviation for the current working directory.
.. is abbreviation for directory directly above current directory.
Absolute pathnames start from the root directory:
/Users/joule/plans/training.pdf or /bin/make or /usr
Relative pathnames start relative to current working directory.
If current working directory is /Users/joule, then:
plans/walks.txt refers to /Users/joule/plans/walks.txt
../sueo refers to /Users/sueo, ../../bin refers to /bin
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Viewing Files and Directories
ls
List the contents of current directory, but don’t show hidden files
(i.e., files whose names start with a dot/period (.) )
ls pathname
List the contents of the directory at pathname
Additional options:
ls -a
List all files, including hidden files
ls -l
Generate a long listing, which includes information about permissions,
file size, etc.
Options can be combined, such as:
ls -al ~/class stuff
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Moving Around the System
cd
Make your home directory (~) the current working directory
cd pathname
Make pathname the current working directory
pwd
Print the name of the current working directory
To find out more about specific commands:
∗ man command
Get a manual page on command
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Working with Files
Basic commands:
cp source target
Make a copy of file source and name the copy target
mv source target
Move (or rename) the file source to target
rm source
Remove the file source
Generalizations:
∗ cp source1 . . . sourcek targetDirectory
Make a copy of each of the files sourcei and place them in the
directory targetDirectory
∗ mv source1 . . . sourcek targetDirectory
Move each of the files sourcei and place them in the directory
targetDirectory
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Some More Commands
Working with directories:
mkdir target
Make a new directory called target
rmdir target
Remove the directory target
Working with text:
more name
Page through text file name, one screenful at a time
less name
A more versatile (and more efficient) version of more
file name
Find out what type of file name is
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