Linux Commands for Oracle DBA

A concise list of essential Linux commands every Oracle DBA should know to efficiently manage database servers, perform system checks, and troubleshoot issues.

System Information

uname -a                      # Show kernel version and system architecture
cat /etc/*release             # Display OS version details
uptime                        # Show system uptime and load averages
top                           # Interactive CPU and memory usage
vmstat                        # Report virtual memory and CPU stats
df -h                         # Display disk space usage in human-readable form
free -m                       # Show memory usage in MB
dmesg                         # Kernel message buffer
iostat                        # CPU and disk I/O statistics
sar                           # Collect and report system activity

User and Group Management

id                            # Display current user UID and GID
whoami                        # Show current logged-in user
who                           # List logged-in users
w                             # Detailed list of logged-in users and processes
groups                        # Display user’s group memberships
su - <user>                   # Switch to another user
sudo -i                       # Switch to root user shell
passwd                        # Change user password

Process Management

ps -ef                        # List all running processes
kill <pid>                   # Terminate process by PID
kill -9 <pid>                # Force terminate process
top                           # Real-time process monitoring

Disk Management

df -h                         # Disk space usage summary
du -sh <dir>                  # Disk usage of directory
lsblk                         # List block devices and partitions
mount | grep <filesystem>     # Show mounted filesystems
umount <device>               # Unmount filesystem
fdisk -l                      # List disk partitions
blkid                         # Show UUIDs of filesystems

Network Commands

ip a                          # Display IP addresses and interfaces
ifconfig                      # Network interface info (older tool)
ping <host>                   # Check network connectivity
traceroute <host>             # Trace network route to host
netstat -tulnp                # List listening ports and associated processes
ss -tulnp                     # Modern alternative to netstat
dig <hostname>                # DNS query
nslookup <hostname>           # DNS lookup tool
curl -I <URL>                 # Fetch HTTP headers
wget <URL>                    # Download files from URL
scp <file> user@host:/path    # Secure copy to remote server
sftp user@host                # Secure FTP session

File Management

ls -lh                        # List files with sizes and permissions
cd /path/to/dir               # Change directory
pwd                           # Show current directory path
cp -r <source> <dest>         # Copy files or directories recursively
mv <source> <dest>            # Move or rename files/directories
rm -rf <file/dir>             # Remove files or directories forcefully
find /path -name <filename>   # Search files by name
grep -r "pattern" /path       # Search recursively for a pattern in files
tar -cvf archive.tar /path    # Create tar archive
tar -xvf archive.tar          # Extract tar archive
zip -r archive.zip /path      # Create zip archive
unzip archive.zip             # Extract zip archive

Oracle Database Commands

sqlplus "/ as sysdba"         # Connect to Oracle DB as SYSDBA
lsnrctl status                # Check Oracle listener status
lsnrctl start                 # Start Oracle listener
lsnrctl stop                  # Stop Oracle listener
export ORACLE_HOME=/u01/app/oracle/product/12.1.0/dbhome_1  # Set ORACLE_HOME
export PATH=$ORACLE_HOME/bin:$PATH                          # Update PATH for Oracle binaries
export ORACLE_SID=ORCL        # Set Oracle SID
tnsping <service_name>        # Test Oracle TNS connectivity
dbstart                       # Start Oracle database services
dbshut                        # Shutdown Oracle database services
rman target /                 # Connect to RMAN for backup/recovery
crsctl status resource -t     # Check RAC Clusterware resource status
srvctl status database -d ORCL # Check Oracle RAC DB status
srvctl start database -d ORCL # Start RAC database
srvctl stop database -d ORCL  # Stop RAC database

Log and Monitoring

tail -f alert_ORCL.log        # Monitor Oracle alert log in real-time
vi /u01/app/oracle/diag/...   # Edit Oracle diagnostic log files
grep "ORA-" alert_ORCL.log    # Search for ORA errors in alert log
df -h | grep /u01             # Check disk usage for Oracle mount points
cat /etc/oratab               # List Oracle instances configured on system

Backup and Scheduling

crontab -l                    # List scheduled cron jobs
crontab -e                    # Edit cron jobs
rsync -av /source /dest       # Synchronize files/directories
rman target /                 # RMAN backup and recovery utility
tar -cvf oracle_backup.tar /u01/app/oracle/datafiles  # Create backup archive

System Administration

systemctl status <service>    # Check status of a service
systemctl restart <service>   # Restart a service
journalctl -xe                # View detailed system logs
history                       # Show command history
alias                         # List defined command aliases
unalias <name>                # Remove an alias
shutdown -h now               # Shutdown system immediately
reboot                        # Reboot system

This list covers essential Linux commands for Oracle DBAs to manage databases, monitor systems, handle backups, and perform administrative tasks efficiently.