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:
/etc/passwd- contains user account information/etc/shadow- contains encrypted passwords for user accounts/etc/group- contains group information/etc/sudoers- determines who can use the sudo command/etc/fstab- specifies filesystems to be mounted on startup/etc/hosts- local hostname to IP address mapping/etc/resolv.conf- specifies DNS server information/etc/sysctl.conf- controls kernel parameters/etc/rc.local- script to run on system startup/etc/init.d/- directory containing system initialization scripts/etc/crontab- system cron jobs/etc/default- default system configuration files/etc/issue- message displayed before login prompt/etc/motd- message displayed after login/etc/exports- specifies directories to be shared via NFS/etc/samba/smb.conf- configuration file for Samba file sharing/etc/ssh/sshd_config- configuration file for the SSH server/etc/sysconfig- system configuration files/etc/security/limits.conf- specifies limits on system resources/etc/security/access.conf- controls access to the system/etc/aliases- email alias file for the mail system/etc/postfix/main.cf- main configuration file for the Postfix mail system/etc/network/interfaces- network interface configuration file/etc/resolv.conf- configuration file for the resolvconf utility/etc/dhcp/dhclient.conf- configuration file for the DHCP client/etc/dhcpd.conf- configuration file for the DHCP server/etc/ntp.conf- configuration file for the NTP daemon/etc/modules- specifies modules to be loaded on startup/etc/bash.bashrc- system-wide bash shell configuration/etc/profile- system-wide shell profile/etc/environment- system-wide environment variables/etc/inputrc- configuration file for the readline library/etc/logrotate.conf- configuration file for log rotation/etc/rsyslog.conf- configuration file for the rsyslog daemon/etc/anacrontab- configuration file for the anacron daemon/etc/timezone- timezone configuration file/etc/localtime- timezone information 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/meminfo- contains information about system memory, including total, free, and used memory/proc/uptime- contains the uptime of the system in seconds/proc/loadavg- contains the load average of the system over the past 1, 5, and 15 minutes/proc/stat- contains various statistics about system activity, including the number of processes, context switches, and interrupts/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/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/self- a symbolic link to the directory corresponding to the current process
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.