Important Linux files

Where you can find performance metrics and configuration settings

On Linux systems, there are several important files that contain performance metrics and configurations. Some of these files include:

/dev/null - a place where to get rid of data
/dev/random - a place where to get high quality random data
/dev/tty0 - a file representing the current terminal
/dev/urandom - a place where to get lower quality random data

Here are some important files in the /etc directory:

/etc/anacrontab - configuration file for the anacron daemon
/etc/aliases - email alias file for the mail system
/etc/bash.bashrc - system-wide bash shell configuration
/etc/crontab - system cron jobs
/etc/default - default system configuration files
/etc/dhcp/dhclient.conf - configuration file for the DHCP client
/etc/dhcpd.conf - configuration file for the DHCP server
/etc/environment - system-wide environment variables
/etc/exports - specifies directories to be shared via NFS
/etc/fstab - specifies filesystems to be mounted on startup
/etc/group - contains group information
/etc/hosts - local hostname to IP address mapping
/etc/init.d/ - directory containing system initialization scripts
/etc/inputrc - configuration file for the readline library
/etc/issue - message displayed before login prompt
/etc/localtime - timezone information file
/etc/logrotate.conf - configuration file for log rotation
/etc/modules - specifies modules to be loaded on startup
/etc/motd - message displayed after login
/etc/network/interfaces - network interface configuration file
/etc/ntp.conf - configuration file for the NTP daemon
/etc/passwd - contains user account information
/etc/postfix/main.cf - main configuration file for the Postfix mail system
/etc/profile - system-wide shell profile
/etc/resolv.conf - specifies DNS server information
/etc/rc.local - script to run on system startup
/etc/rsyslog.conf - configuration file for the rsyslog daemon
/etc/samba/smb.conf - configuration file for Samba file sharing
/etc/security/limits.conf - specifies limits on system resources
/etc/security/access.conf - controls access to the system
/etc/shadow - contains encrypted passwords for user accounts
/etc/ssh/sshd_config - configuration file for the SSH server
/etc/sudoers - determines who can use the sudo command
/etc/sysctl.conf - controls kernel parameters
/etc/sysconfig - system configuration files
/etc/timezone - timezone configuration file

Here are some important files in the /proc directory:

/proc/cpuinfo - contains information about the processor, including its type, speed, and available features
/proc/devices - lists the device files in the /dev directory and their corresponding major and minor device numbers
/proc/filesystems - lists the filesystem types supported by the kernel
/proc/kcore - a copy of the kernel's physical memory
/proc/kmsg - contains kernel messages
/proc/loadavg - contains the load average of the system over the past 1, 5, and 15 minutes
/proc/meminfo - contains information about system memory, including total, free, and used memory
/proc/self - a symbolic link to the directory corresponding to the current process
/proc/stat - contains various statistics about system activity, including the number of processes, context switches, and interrupts
/proc/sys - contains various system parameters that can be modified using sysctl
/proc/sysrq-trigger - a file that can be used to perform emergency actions when the system is in a critical state
/proc/uptime - contains the uptime of the system in seconds

It is important for a Linux administrator to be familiar with these and other configuration files, as they contain important information about the system and its settings.