[python] OS operating system libraries for Python os module large sword (full)

Brief introduction

os module provides most of the functionality of the operating system interface functions. When the module is introduced into the os, it will be adaptive to a different operating system platforms, the corresponding operation according to different platforms, the python programming, and often files, directories dealing with time and can become os module, this section os module provides functions will be detailed interpretation

1. Return type of operating system: posix is ​​linux operating system, nt is the windows operating system

print(os.name)
print('Linux' if os.name == 'posix' else 'Windows')

posix
Linux

2. Details of the operating system

info = os.uname()
print(info)
print(info.sysname)
print(info.nodename)

posix.uname_result(sysname='Linux', nodename='foundation1.ilt.example.com', release='3.10.0-514.el7.x86_64', version='#1 SMP Wed Oct 19 11:24:13 EDT 2016', machine='x86_64')
Linux
foundation1.ilt.example.com

3. The system environment variables

print(os.environ)
print(os.environ.get('PATH'))               #通过key值获取环境变量对应的value值

environ({'PATH': '/usr/local/bin:/usr/local/sbin:/usr/bin:/usr/sbin:/bin:/sbin:/home/kiosk/.local/bin:/home/kiosk/bin', 'XAUTHORITY': '/run/gdm/auth-for-kiosk-VxJi8Q/database', 'IMSETTINGS_MODULE': 'none', 'HISTCONTROL': 'ignoredups', 'XMODIFIERS': '@im=ibus', 'GDMSESSION': 'gnome-classic', 'DBUS_SESSION_BUS_ADDRESS': 'unix:abstract=/tmp/dbus-Pz5VvDs6Nd,guid=dda5a3ee1f3848808f16852b5d004efd', 'XDG_CURRENT_DESKTOP': 'GNOME-Classic:GNOME', 'MAIL': '/var/spool/mail/kiosk', 'SSH_AGENT_PID': '1616', 'LD_LIBRARY_PATH': '.:', 'SESSION_MANAGER': 'local/unix:@/tmp/.ICE-unix/1446,unix/unix:/tmp/.ICE-unix/1446', 'USERNAME': 'kiosk', 'LOGNAME': 'kiosk', 'PWD': '/home/kiosk/PycharmProjects/2019python', 'PYCHARM_HOSTED': '1', 'WINDOWID': '31457287', 'PYTHONPATH': '/home/kiosk/PycharmProjects/2019python', 'LESSOPEN': '||/usr/bin/lesspipe.sh %s', 'SHELL': '/bin/bash', 'QT_GRAPHICSSYSTEM_CHECKED': '1', 'GNOME_DESKTOP_SESSION_ID': 'this-is-deprecated', 'IMSETTINGS_INTEGRATE_DESKTOP': 'yes', 'XDG_SESSION_DESKTOP': 'gnome-classic', 'LS_COLORS': 'rs=0:di=38;5;27:ln=38;5;51:mh=44;38;5;15:pi=40;38;5;11:so=38;5;13:do=38;5;5:bd=48;5;232;38;5;11:cd=48;5;232;38;5;3:or=48;5;232;38;5;9:mi=05;48;5;232;38;5;15:su=48;5;196;38;5;15:sg=48;5;11;38;5;16:ca=48;5;196;38;5;226:tw=48;5;10;38;5;16:ow=48;5;10;38;5;21:st=48;5;21;38;5;15:ex=38;5;34:*.tar=38;5;9:*.tgz=38;5;9:*.arc=38;5;9:*.arj=38;5;9:*.taz=38;5;9:*.lha=38;5;9:*.lz4=38;5;9:*.lzh=38;5;9:*.lzma=38;5;9:*.tlz=38;5;9:*.txz=38;5;9:*.tzo=38;5;9:*.t7z=38;5;9:*.zip=38;5;9:*.z=38;5;9:*.Z=38;5;9:*.dz=38;5;9:*.gz=38;5;9:*.lrz=38;5;9:*.lz=38;5;9:*.lzo=38;5;9:*.xz=38;5;9:*.bz2=38;5;9:*.bz=38;5;9:*.tbz=38;5;9:*.tbz2=38;5;9:*.tz=38;5;9:*.deb=38;5;9:*.rpm=38;5;9:*.jar=38;5;9:*.war=38;5;9:*.ear=38;5;9:*.sar=38;5;9:*.rar=38;5;9:*.alz=38;5;9:*.ace=38;5;9:*.zoo=38;5;9:*.cpio=38;5;9:*.7z=38;5;9:*.rz=38;5;9:*.cab=38;5;9:*.jpg=38;5;13:*.jpeg=38;5;13:*.gif=38;5;13:*.bmp=38;5;13:*.pbm=38;5;13:*.pgm=38;5;13:*.ppm=38;5;13:*.tga=38;5;13:*.xbm=38;5;13:*.xpm=38;5;13:*.tif=38;5;13:*.tiff=38;5;13:*.png=38;5;13:*.svg=38;5;13:*.svgz=38;5;13:*.mng=38;5;13:*.pcx=38;5;13:*.mov=38;5;13:*.mpg=38;5;13:*.mpeg=38;5;13:*.m2v=38;5;13:*.mkv=38;5;13:*.webm=38;5;13:*.ogm=38;5;13:*.mp4=38;5;13:*.m4v=38;5;13:*.mp4v=38;5;13:*.vob=38;5;13:*.qt=38;5;13:*.nuv=38;5;13:*.wmv=38;5;13:*.asf=38;5;13:*.rm=38;5;13:*.rmvb=38;5;13:*.flc=38;5;13:*.avi=38;5;13:*.fli=38;5;13:*.flv=38;5;13:*.gl=38;5;13:*.dl=38;5;13:*.xcf=38;5;13:*.xwd=38;5;13:*.yuv=38;5;13:*.cgm=38;5;13:*.emf=38;5;13:*.axv=38;5;13:*.anx=38;5;13:*.ogv=38;5;13:*.ogx=38;5;13:*.aac=38;5;45:*.au=38;5;45:*.flac=38;5;45:*.mid=38;5;45:*.midi=38;5;45:*.mka=38;5;45:*.mp3=38;5;45:*.mpc=38;5;45:*.ogg=38;5;45:*.ra=38;5;45:*.wav=38;5;45:*.axa=38;5;45:*.oga=38;5;45:*.spx=38;5;45:*.xspf=38;5;45:', 'SHLVL': '3', 'QT_PLUGIN_PATH': '/usr/lib64/kde4/plugins:/usr/lib/kde4/plugins', 'QT_IM_MODULE': 'ibus', 'HISTSIZE': '1000', 'TERM': 'xterm-256color', 'XFILESEARCHPATH': '/usr/dt/app-defaults/%L/Dt', 'LANG': 'en_US.utf8', 'XDG_SESSION_ID': '1', 'DISPLAY': ':0', '_': '../jre/jre/bin/java', 'GDM_LANG': 'en_US.utf8', 'PYTHONIOENCODING': 'UTF-8', 'DESKTOP_SESSION': 'gnome-classic', 'GPG_AGENT_INFO': '/run/user/1000/keyring/gpg:0:1', 'USER': 'kiosk', 'XDG_MENU_PREFIX': 'gnome-', 'WINDOWPATH': '1', 'VTE_VERSION': '3804', 'XDG_SEAT': 'seat0', 'SSH_AUTH_SOCK': '/run/user/1000/keyring/ssh', 'PYTHONUNBUFFERED': '1', 'HOSTNAME': 'foundation1.ilt.example.com', 'NLSPATH': '/usr/dt/lib/nls/msg/%L/%N.cat', 'GNOME_SHELL_SESSION_MODE': 'classic', 'KDEDIRS': '/usr', 'XDG_RUNTIME_DIR': '/run/user/1000', 'XDG_VTNR': '1', 'HOME': '/home/kiosk'})
/usr/local/bin:/usr/local/sbin:/usr/bin:/usr/sbin:/bin:/sbin:/home/kiosk/.local/bin:/home/kiosk/bin

4 determines whether the absolute path

print(os.path.isabs('/tmp/ffff'))
print(os.path.isabs('hello.jog'))

True
False

5. Get the current path

print(os.getcwd())
/home/kiosk/PycharmProjects/2019python

6. The three ways to generate absolute path

print(os.path.abspath('hello.png'))
print(os.path.join(os.path.abspath('.'),'hello.jpg'))       ## .表示当前路径
print(os.path.join('/home/kiosk','hello.jpg'))

/home/kiosk/PycharmProjects/2019python/hello.png
/home/kiosk/PycharmProjects/2019python/hello.jpg
/home/kiosk/hello.jpg

7. Gets the directory or file name

filename = '/1234/year/month/day/hello.jpg'
print(os.path.basename(filename))
print(os.path.dirname(filename))

hello.jpg
/1234/year/month/day

8. Return all the file names and directory names in the specified directory, a list is returned

print(os.listdir('img'))
['file1']

9. separation and file name extension

print(os.path.splitext('hello.jpg'))

10. The directory name and file name separated

print(os.path.split('/tmp/hello/hello.jpg'))

11. Create a directory [mkdir / mkdir -p]

os.mkdir('img')
os.makedirs('img/file1/file2')

You can not recursively delete a directory, delete layer by layer

 os.rmdir('img')
 
 OSError: [Errno 39] Directory not empty: 'img'

12. You can delete empty directories recursively multi-layer, if there are files in the directory can not be deleted

os.removedirs('img/file1/file2')

13. Create File Delete File

os.mknod('00_ok.txt')
os.remove('00_ok.txt')

14. Rename the file

os.rename('data.txt','data1.txt')

15. whether a file or directory exists

print(os.path.exists('ips.txtyyyy'))
print(os.path.exists('/home/kiosk/PycharmProjects/2019python/ips.txt'))

False
True

16. determine whether the file or directory

print(os.path.isfile('ips.txt'))
print(os.path.isdir('img'))

17. To change the current directory to the specified directory

print(os.getcwd()) 
path='/tmp'
os.chdir(path)
print(os.getcwd())

/home/kiosk/PycharmProjects/2019python
/tmp

18. File Information

Access: Time file was last accessed; When the editor to open the file, using the cat, more, less, grep, sed reads the contents of the file will refresh time [Access using ls -lu can read the current Access time ]

Modify: contents of the file was last modified time; When modifying the file content Modify time will refresh
Usage ls -l command displays the last time Modify]

Change: file attribute was last modified time, perform mv, chmod, chgrp command to a file or directory you will refresh time [Change can be viewed using the ls -lc last time] Change
------ ------------------------ ---------------- practice
in the current directory new directory img, which contains multiple files, the file names are different (X4G5.png)
a list of all currently img suffix name changed to the end of .jpg .png

import random
import string
import os

def gen_code(len=4):
    # 随机生成4位验证码
    li = random.sample(string.ascii_letters+string.digits,len)
    return ''.join(li)
def create_file():
    # 随机生成100个验证码
    li = {gen_code() for i in range(100)}
    os.mkdir('img')
    for name in li:
        os.mknod('img/' + name + '.png')

create_file()

def modify_suffix(dirname,old_suffix,new_suffix):
    """
    :param dirname:操作的目录
    :param old_suffix: 之前的后缀名
    :param new_suffix: 新的后缀名
    :return:
    """
    # 1.判断查找的目录是否存在，如果不存在，报错
    if os.path.exists(dirname):
        # 2.找出所有以old_suffix(.png)结尾的文件
        pngfile = [filename for filename in os.listdir(dirname)
                   if filename.endswith(old_suffix)]
        # 3.将后缀名和文件名分开，留下文件名
        basefiles = [os.path.splitext(filename)[0]
                     for filename in pngfile]
        # 4.重命名文件
        for filename in basefiles:
            oldname = os.path.join(dirname,filename+old_suffix)
            newname = os.path.join(dirname,filename+new_suffix)
            os.rename(oldname,newname)
            print('%s命名为%s成功' %(oldname,newname))
    else:
        print('%s不存在,不能操作...' %(dirname))

modify_suffix('redhat','.jpg','.png')