Learning record 004-Directory and file extension

First, Directory
1. System log file storage/var/log/messages, the information inside the automatic polling, often look at this file, the system has a problem, first look at this file
2.var/log/secure//record log in information by weekly polling
3.var/log/wtmp//Record last information input last displays information about the login account or W who Lastlog
4.var/spool/cron/root//Timed task Crontab-l the same effect
5.var/spool/clientmqueue//sendmail The file directory of temporary mail sometimes causes the inode to be full.
6.proc//virtual directory is a mapping of memory
Proc/version//Kernel version
Proc/sys/kernel//System kernel function
etc/sysctl.conf///kernel parameter configuration path is placed here permanently proc/sys/net/ipv4/tcp_max_tw_buckets put it into effect here when run, a lot of people want to start on the boot will open/etc/ Rc.local inside add echo 0 >proc/sys/net/ipv4/tcp_max_tw_buckets, this kernel tuning is the same
Proc/cpuinfo//processor information, such as type, manufacturer and model etc.
Proc/meminfo//System memory Information
Proc/devices//List of all devices configured by the current running kernel
PROC/DMA//channel of DMA currently in use
Proc/interrupts//The interrupt being used and the number of interrupts that have been made, this advanced tuning to the back will involve
Proc/ioports//I/O port currently in use
PROC/LOADDAVG//System load information (the busy situation of the system, more accurate, but not enough detailed system indicators). Results of uptime
7. In Linux ls-al//a display hidden files, there will be a point to display the end of such as. Sh This is the hidden file

Ii. Linux file extension
1.windows file extension Pictures: Jpg,jpeg,pug,bmp,gif etc
Content extension: doc,docx,txt,pdf
2.linux system, all documents, ls-l
-rwxrwxr-x. 1 Root2 root2 June 03:18 a.sh
Drwxr-xr-x. 2 Root2 root2 4096 June 19:06 Desktop
-(regular file) common file Touch CP, etc. tool commands created are normal files, all with RM can be deleted
Continue to divide: plain text files (ASCLL) such as etc/hosts binary file z execute command file (binary) data format file data record in, var/log/wtmp file is log logged in data
So how to differentiate these files
File/etc/hosts or with other files can be
[Email protected] ~]$ file/var/log/w
Wpa_supplicant.log wtmp
[Email protected] ~]$ file/var/log/wtmp
/var/log/wtmp:data
[Email protected] ~]$ file/etc/hosts
/etc/hosts:ascii text
[Email protected] ~]$ File/bin/ls
/bin/ls:elf 64-bit LSB executable, x86-64, version 1 (SYSV), dynamically linked (uses shared libs), for Gnu/linux 2.6.18, Stripped
d (directory) directory file View catalog file Ls-ld ls-f to the directory is to add "/" at the end
Character devices and block devices
Find/dev-type b-exec ls-l {} \;
Find/dev-type B|xargs Ls-l
[Email protected] ~]# Ll-al/dev/tty
crw-rw-rw-. 1 root TTY 5, 0 June 03:37/dev/tty//c the beginning of the character device character device refers to a device that transmits characters in the I/O transmission, such as a keyboard, printer, and so on. Note that in characters, it does not necessarily mean that it is in bytes, because the encoding rules stipulate that 1 characters are 16 bits and 2 bytes in total.
[Email protected] ~]# LL-AL/DEV/SDA
BRW-RW----. 1 root Disk 8, 0 June 01:45/DEV/SDA//b start with a block device disk, optical drive Mknod Kaka C 5 1, creating a Kaka block device
Socket interface File: Mysql.sock, data connection between networks
[Email protected] ~]# Ll/dev/log
srw-rw-rw-. 1 root root 0 June 17:45/dev/log
S.
Symbolic Link File
[Email protected] ~]# LS-LD/ETC/INIT.D
lrwxrwxrwx. 1 root root One June 02:43/etc/init.d-Rc.d/init.d//l
3.linux files can have no extension, primarily for compatibility with Windows
. Tar. tar.gz. tgz. zip. tar.bz means that the compressed file creation command is generally tar,gzip,uzip
. SH represents a shell script file, a program developed through the shell language
. pl represents Perl language files, programs developed in the Perl language
. py represents a Python language file that is developed through the Python language
. html. htm. php. jsp. Do represents a Web language file
. conf represents the system's configuration file
. RPM indicates RPM installation package file

Learning record 004-Directory and file extension