One command line includes 4 parts: Command Name、Options、Arguments、Extras .
man <command-name> : Give the manual of this command.
/ : Root directory
.. : Parent directory.
pwd : Print working directory, which will show the absolute path of current folder.
ls : List directory contents. Ls –la : List all contents including hidden contents.
cd : Change directory.
mkdir : Make directories.
rmdir: Remove directories.
mvdir: Move or rename a directory.
处理特殊字符(space, bracket, quotation mark, !, $, &, *, ;, , …)
: Use back slash before the character. cd Punlic/Drop Box/ ( = cd “Public/Drop Box”).
cp : Copy files.
mv : Move files.
rm : Remove files
vi: or vim : A programmers text editor
nano: Nano's another editor, an enhanced free pico clone.
cat : Concatenate and print files. It reads files sequentially, writing them to the standard output.
cat file1 : Will print the contents of file1 to the standard output.
cat file1 file2 > file3: Will sequentially print the cntents of file1 and file2 to the file3.
cat file1 – file2 – file3: ???
od: Octal, decimal, hex, ASCII dump
which: Locate a program file in the user’s path.
find : find . -name "*.c" -print
file: Determine file type.
head: Display first lines of a file. head -10 filename.
tail: Display the last part of a file.
cut: Cut out selected portions of each lie of a flie.
colrm: Remove columns from a file. colrm 8 20 filename
diff: Compare files line by line.
sort: Sort lines of text file.
uniq: Report or filter out repeated lines in a file.
comm: Select or regject lines common to two files.
wc: Word, line, character, and byte count.
nl: Line numbering filter. nl file1 > file2
ps : Process status ps u
kill : Terminate or signal a process. kill -9 30142
The kill utility sends a signal to the processes specified by the pid operand(s).
Only the super-user may send signals to other user's processes.
Some of the more commonly used signals:
1 HUP (hang up)
2 INT (interrupt)
6 ABRT (abort)
9 KILL (non-catchable, non-ignorable kill)
14 ALRM (alarm )
15 TERM (software termination signal)
date: Display or set date and time.
cal: Display a calendar and the date of easter cal 4 2015.
time: time command execution (totoal time elapsed.)
w: Display who is logged in and what they are doing.
su : Substitute user identify.
Sudo : Substitute user do, or super user do. It allows a permitted user to execute a command as the superuser or another user.