preface
This article mainly studies several common file commands, ls, file and less.
1, Some additional information about the command
Options and parameters
Usually, a command is followed by one or more options, and commands with different options have different functions. In addition, the command will be followed by one or more parameters. These parameters are the object of the command (I feel a little similar to calling the function), so most commands look as follows:
command -options arguments
Most commands use the option of adding a hyphen before a single character, such as -; However, many commands also support the long option of adding two hyphens before a single character, and many commands also allow multiple short options to be used together (this is fun).
Long list format
for instance:
drwxr-xr-x 2 yrf-tan yrf-tan 4096 5 June 20-16:30 Documents drwxr-xr-x 2 yrf-tan yrf-tan 4096 5 June 22:20 Downloads -rw-r--r-- 1 yrf-tan yrf-tan 8980 5 June 18-22:41 examples.desktop -rw-rw-r-- 1 yrf-tan yrf-tan 83325072 5 August 10:29 google-chrome-stable_current_amd64.deb
| field | meaning |
|---|---|
| -rw-r-r-- ,drwxr-xr-x | Access to the file. The first character indicates the type of file. Between different types, the "-" at the beginning indicates that the file is an ordinary file and d indicates a directory. The next three characters represent the access rights of the file owner, the next three characters represent the access rights of the members of the group to which the file belongs, and the last three characters represent the access rights of other owners. |
| 1 | Number of file hard links |
| Yrf Tan (first) | User name of the file owner (yrf Tan is the user name of my computer, and your user name will be displayed on your computer) |
| Yrf Tan (second) | The name of the user group to which the file belongs |
| 4096 | File size in bytes |
| 16:30, May 20 | Date and time when the file was last modified |
| Documents | file name |
2, Several common file commands
1,ls
Purpose: ls you can view the contents of the directory and determine the attributes of various files and directories
Common options for ls command:
| option | Long option | meaning |
|---|---|---|
| -a | –all | List all files, including those starting with a dot, which are usually not listed (such as hidden files) |
| -d | –directory | Usually, if a directory is specified, the ls command lists the contents of the directory rather than the directory itself. Use this option in conjunction with - l to view the details of the directory rather than the contents of the directory. |
| -F | –classify | Option adds a type indicator after each listed name (for example, a slash if the name is a directory name) |
| -h | –human-readable | List in long format and display the file size in a human readable manner rather than in bytes |
| -l | Display results in long format | |
| -r --reverse | Display the results in reverse order. Typically, the ls command displays the results in ascending alphabetical order | |
| -S | Sort results by file size | |
| -t | Sort by modification time |
These commands can also be combined
Output example:
ls:
yrf-tan@yrftan-Lenovo-G50-70m:~$ ls deepin-wine-for-ubuntu examples.desktop Public music Desktop google-chrome-stable_current_amd64.deb Templates Documents Music Videos Downloads Pictures download
ls -a:
yrf-tan@yrftan-Lenovo-G50-70m:~$ ls -a . Music .. .pam_environment .bash_history Pictures .bash_logout .pki .bashrc .presage .cache .profile .config Public .dbus .sogouinput deepin-wine-for-ubuntu .sudo_as_admin_successful Desktop .swo Documents .swp Downloads Templates examples.desktop .thunderbird .gnupg Videos google-chrome-stable_current_amd64.deb .viminfo .ICEauthority .xinputrc .local download .mozilla music
ls -d:
yrf-tan@yrftan-Lenovo-G50-70m:~$ ls -d . yrf-tan@yrftan-Lenovo-G50-70m:~$ ls -d .swp .swp
ls -F:
yrf-tan@yrftan-Lenovo-G50-70m:~$ ls -F deepin-wine-for-ubuntu/ google-chrome-stable_current_amd64.deb Videos/ Desktop/ Music/ download/ Documents/ Pictures/ music/ Downloads/ Public/ examples.desktop Templates/
ls -h:
yrf-tan@yrftan-Lenovo-G50-70m:~$ ls -h deepin-wine-for-ubuntu examples.desktop Public music Desktop google-chrome-stable_current_amd64.deb Templates Documents Music Videos Downloads Pictures download yrf-tan@yrftan-Lenovo-G50-70m:~$ ls --human-readable deepin-wine-for-ubuntu examples.desktop Public music Desktop google-chrome-stable_current_amd64.deb Templates Documents Music Videos Downloads Pictures download
ls -l:
yrf-tan@yrftan-Lenovo-G50-70m:~$ ls -l total 81436 drwxrwxr-x 17 yrf-tan yrf-tan 4096 5 September 19-22:34 deepin-wine-for-ubuntu drwxr-xr-x 2 yrf-tan yrf-tan 4096 5 June 20-16:30 Desktop drwxr-xr-x 2 yrf-tan yrf-tan 4096 5 June 20-16:30 Documents drwxr-xr-x 2 yrf-tan yrf-tan 4096 5 June 22:20 Downloads -rw-r--r-- 1 yrf-tan yrf-tan 8980 5 June 18-22:41 examples.desktop -rw-rw-r-- 1 yrf-tan yrf-tan 83325072 5 August 10:29 google-chrome-stable_current_amd64.deb drwxr-xr-x 2 yrf-tan yrf-tan 4096 5 June 20-16:30 Music drwxr-xr-x 2 yrf-tan yrf-tan 4096 5 June 20-16:30 Pictures drwxr-xr-x 2 yrf-tan yrf-tan 4096 5 June 20-16:30 Public drwxr-xr-x 2 yrf-tan yrf-tan 4096 5 June 20-16:30 Templates drwxr-xr-x 2 yrf-tan yrf-tan 4096 5 June 20-16:30 Videos drwxr-xr-x 2 yrf-tan yrf-tan 4096 5 June 18-23:13 download drwxr-xr-x 3 yrf-tan yrf-tan 4096 5 June 18-22:53 music
ls -r:
yrf-tan@yrftan-Lenovo-G50-70m:~$ ls -r music Pictures Documents download Music Desktop Videos google-chrome-stable_current_amd64.deb deepin-wine-for-ubuntu Templates examples.desktop Public Downloads
ls -S:
yrf-tan@yrftan-Lenovo-G50-70m:~$ ls -S google-chrome-stable_current_amd64.deb Desktop Music Templates music examples.desktop Documents Pictures Videos deepin-wine-for-ubuntu Downloads Public download
ls -t:
yrf-tan@yrftan-Lenovo-G50-70m:~$ ls -t Downloads Public music Videos Desktop examples.desktop Pictures Templates google-chrome-stable_current_amd64.deb Music deepin-wine-for-ubuntu Documents download
2,file
Use the file command to determine the file type, because the file name in the Linux system does not need to reflect the file content. When we need to view the short description of a file, we can call the file command, file filename
, after calling, the file command will print out a brief description of the contents of the file. For example:
yrf-tan@yrftan-Lenovo-G50-70m:~$ file Pictures Pictures: directory
3,less
Use the less command to view the contents of the file. The less command is a program for viewing text files. The less command is used as follows:
less filename
Use the less command to view the file, scroll the file back and forth, and press q to exit the less program.
| command | function |
|---|---|
| G | Jump to the end of the text file |
| lG or g | Jump to the beginning of the text file |
| /charecters | Find the specified amount string forward |
| n | Look forward to the next occurrence of the string, which is the previously specified search |
| h | show this help screen |
| q | Exit less |
Origin of less command:
The less program is designed to replace the more program in early UNIX. The name less comes from "less is more"
summary
This article mainly introduces some commands ls, file and less for viewing file information, as well as the options and parameters of the command and a description of the long file format.