Yandex Big Data Essentials Week1 Unix Command Line Interface Processes managing

free

displays the total amount of free and used memory
free [options]

top

provides a dynamic real-time view of a running system
top [options]

ps

provides snapshot of the status of currently running processes
ps [options]

kill

sends a signal to a process
kill [-s][-l] %pid

nice

runs a command with a modified scheduling priority
nice [OPTION] [COMMAND [ARG] …]

课程总结:

Command	Description
awk	interpreted programming language text processing
awk -F	set the separator
cat	Display the contents of a file at the command line,is also used to copy and or append text files into a document. Named after it’s function to con-cate-nate files.
cd	Change the current working directory.Also known as chdir
cd /	Change the current directory to root directory
cd ..	Change the current directory to parent directory
cd ~	Change the current directory to your home directory
cp	Make copies of files and directories
cp -r	Copy directories recursively
cut	Drop sections of each line fo iniput by bytes,characters, or fields,separated by a delimiter (the tab character by default)
cut -d -f	-d is for delimiter instead of tab character,-f select only those fields(ex.: ” cut -d “,” -f1 multilined_file.txt” -will mean that we select only the first field from each comma-separated line in the file
du	Estimate (and display) the file space usage -space used under a particular directory or file on a file system
df	Display the amount of available disk space being used by file systems.
df -h	use human readable format
free	Display the total amount of free and used memory(use vm_stat instead on MacOS).
free -m	Display the amount of memory in megabytes
feee -g	Display the amount of memory in gigabytes
grep	Process text and print any lines which match a regular expression(“global regular expression print”)
head	Print the beginning of a text file or piped data.By default,outputs the first 10 lines of its input to the commannd line
head -n	Output the first n lines of input data(ex: “head -5 multilined_file.txt”)
kill	Send a signal to kill a process. The default signal for kill is TERM(which will terminate the process)
less	is similar to more,but has extended capability of allowing both forward and backward navigation through the file
ls	List the content of a directory
ls -l	List the contents of a directory + use a long format,displaying Unix file types,permissions,number of hard links, owner,group,size,last-modified data and filename.
ls -lh	List the contents of a directory + print sizes in human readable format.(eg. 1k,234M,2G,etc)
ls -lS	Sort by file size
man	Display the man pages with provide documentation about commands,system calls,library routines and the kernel
mkdir	Create a directory on a file system.
more	Display the contents of a text file one screen at a time
mv	Rename files or directories or move them to a different directory
nice	Run a command with a modified scheduling priority.
ps	Provide information about the currently running process,including their process identification numbers (PIDS)(“process status”)
ps a	select all processes except both session leader and processes not associated with terminal.
pwd	Abbreviated from “print working directory”,pwd writes the full pathname of the current working directory.
rm	Remove files or directory
rm -r	Remove directories and their contents recursively.
sort	Sort the contents of a text file.
sort -r	Sort the output in the reverse order. Reverse means - to reverse the result of comparsions
sort -k	-k or –key=POS1[,POS2] Start a key at POS1 (origin 1), end it at POS2 (default end of the line) (ex.: “sort -k2,2 multilined_file.txt”).
sort -n	Compare according to string numerical value.
tail	Print the tail end of a text file or piped data. Be default, outputs the last 10 lines of its input to the command line.
tail -n	Output the last n lines of input data (ex.: “tail -2 multilined_file.txt”).
top	Produce an ordered list of running processes selected by user-specified criteria, and updates it periodically.
touch	Update the access date and or modification date of a file or directory or create an empty file.
tr	Replace or remove specific characters in its input data set (“translate”).
tr -d	Delete characters, do not translate.
vim	Is a text editor (“vi improved”). It can be used for editing any kind of text and is especially suited for editing computer programs.
wc	Print a count of lines, words and bytes for each input file (“word count”)
wc -c	Print only the number of characters.
wc -l	Print only the number of lines.