tar can pack multiple archives and then use them to compress
gzip unzip archive
bzip2 command for better decompression ratio
Dump backup tool, you can back up files by level dump -0u -f The path name of the file to be backed up The file to be backed up
restore restores backup files
echo reads out the variable, you need to add $ before the variable, the assignment of the variable, the double quotation mark means it is still the variable value, the single quotation mark is plain text, and the ·· will be executed first
export turns variables into environment variables
declare declares the variable type
ulimit restricts the conditions of the file system, it is better to only allow 10 people to access a certain file at the same time
cut -d "separator" -f segment number Take out a segment of data in the line
grep analyze the data and take out what you need
sort sort
uniq remove duplicate data
wc query the number of lines, words, and characters in a file
tee double redirection can save a certain message in the data stream processing