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. |