Status query
View memory
free optional parameter -m -g
Disk usage
df optional parameter -h
Observe which application port is used (detailed output information, no output if not occupied)
lsof -i: port number
For example, check which program is occupied by 8080
If it is occupied, the occupied program will be output, otherwise no output
Text manipulation
The text operation commands can be combined at will with the pipe character to play the biggest role
cat
Directly output all the contents of the file. When the file content is large, you can use grep to filter
cat fileName
more
more fileNmae
Enter (roll down one line)
Space (scroll down one screen)
Q (Exit command)
B (scroll up one screen)
less
less fileName
PageUp key to page up
PageDown key to page down
tail
View the last line of the file, the last 10 lines of the default array
# Output the last 100 lines of the file
tail -n 100 fileName
# View the last content of the file in real time, generally used to view the log in real time
tail -f fileName
head
Similar to tail, output header
head fileName
# The first 100 lines of the output file
head -n 100 fileName
uniq
To deduplicate the content, only the adjacent and the same deduplication, if you want to deduplicate globally, you need to sort by sort first
# File sort and deduplication
cat fileName | sort | uniq
# File sort and deduplication, and output the number of occurrences of each line
cat file | sort | uniq -c
sort
Sort the content, the data is arranged in lexicographic order, if you want to sort by value, add -n option
cat fileName | sort
wc
# How many lines in the file
wc -l fileName
# How many words in the file
wc -w fileName
# How many bytes in the file
wc -c fileName
# How many characters in the file
wc -m fileName
Can be combined with pipe
cat fileName | wc -l
grep
The first form
grep [option] [pattern] [file1,file2]
For example, find the line containing content in show.txt
grep content show.txt
The second form
command | grep [option] [pattern]
If viewing a service information
ps -ef | seized mongo
For example, find the line containing content in show.txt
cat show.txt | grep content
The internet
Remote file transfer scp
First ensure that the server and ssh can jump to each other
Command format
scp -r source directory username @ip: target directory
The role of the -r parameter is to recursively copy the source directory, and the subdirectories and files in the copied directory
scp -r ~/app hadoop@hadoop001:~/
scp -r ~/app hadoop@hadoop002:~/
## 分发环境变量
scp ~/.bash_profile hadoop@hadoop001:~/
scp ~/.bash_profile hadoop@hadoop002:~/
Check if the network is connected
ping www.baidu.com
Check if the port is open
ping www.baidu.com -p 80
download file
wget file address