-- Get all process information and write it to the file test1107.txt (if the file test1107.txt does not exist, it will be created automatically, if it already exists, the original content will be cleared, and then the process information will be written).
ps -ef >test1107.txt
-- Get all process information and write it to the file test1107.txt (if the file test1107.txt does not exist, it will be created automatically, if it already exists, the process information will be appended to the end of the file, the original content will not be overwritten ).
ps -ef >> test1107.txt
-- Write "test" to file test1107.txt
echo 'test' >test1107.txt
-- Write the contents of the file test1107.txt to test1108.txt (equivalent to copy)
cat test1107.txt > test1108.txt