Linux_Commands

Helpful Basic Linux Commands for Developers

Java Processes

• jps: Shows all Java processes running on the machine.
• ps -eLf: Displays all running threads.
• ps -ef / -efH: Lists processes for runtime execution.
• ps -ef | grep java: Checks all Java processes.
• ps -a: Checks if Asterisk is running.

Scheduler and Sessions

• crontab -e: Edits the scheduler in Linux.
• screen -ls, screen -r, screen -S vas: Manages Putty sessions.
• lokkit: Opens firewall settings.

********************************************************

Download Barcode scanner for small shops

Asterisk & Dahdi Commands

b
asterisk -vvc 
dahdi_tools 
#dahdi_cfg -vv  # Reset channels 
#asterisk -vvc  # Start Asterisk 
#asterisk -r    # Reconnect to Asterisk 
#asterisk -rx "dahdi show status"  # Remote execution of Asterisk CLI commands 
cli> ss7 show linkset 1 
cli> dahdi show channels 
cli> core show channels 
cli> ss7 set debug on linkset 1 
cli> ss7 block linkset 1 
cli> ss7 unblock linkset 1 
cli> ss7 block cic 1 15  # Example command

---

Linux Commands for Oracle & MySQL

Oracle

bash
cd /home/<UserName>/oracle/product/10.2.0/db_1/bin/  # Path for Oracle in Linux 
cmd/> dbca  # Open Oracle Database Creation 
su <UserName> sqlplus username/password@connect_identifier 
sql> create user identified by password; 
sql> grant dba to user; 
sql> grant all privileges to user;

MySQL

bash
mysql> repair table table_name;  # Repair corrupted tables 
mysql> GRANT ALL ON .* TO root@'ip' IDENTIFIED BY '';  # Allow connections from other IP 
mysql> source path/filename.txt  # Execute queries from a file

mysql> UPDATE mysql.user SET Password=PASSWORD('nbuser') WHERE User = 'root'; 
mysql> FLUSH PRIVILEGES;
mysql> optimize table tblName;  # Defrag table

---

Linux System Management

System Configuration

• setup: Configures IP and gateway in Linux.
• route: Checks IP and gateway.
• traceroute IP: Traces route from source to destination IP.
• service --status-all: Checks the status of all running processes.
• chkconfig servicename on: Sets a service to start automatically on system restart.
• yum install php-mysql php-apache: Installs and configures PHP with MySQL and Apache.
• /sbin/chkconfig --list | grep mysqld: Checks autorun services at bootup.
• chkconfig --add tomcat: Autostart Tomcat at /etc/init.d/tomcat.
• chkconfig --level 345 tomcat on: Sets run levels for Tomcat.

Firewall and Networking

bash
service iptables status
chkconfig iptables on
service iptables start
service iptables stop
service iptables restart
iptables -A INPUT -s -j DROP  # Block incoming traffic from an IP
iptables -A OUTPUT -s -j DROP  # Block output connection to an IP
iptables -A OUTPUT -p icmp --icmp-type 8 -j DROP  # Disable ping

Miscellaneous Commands

nmap -sS -O 127.0.0.1  # Check all opened ports
dmidecode -t system  # Display system information
wget completeURL  # Download from a link

---

File and Directory Management

bash
chown -R username /path  # Provide permission to a user for the specified path
chown root:root /tmp; chmod 1777 /tmp  # Resolve issues with writing to a directory
/etc/init.d/mysqld start  # Start MySQL service

File Operations

bash
cat *.txt > xyz.txt  # Concatenate contents of multiple text files into a single file
rm filename.extension  # Remove a file using Putty
mv folder destination  # Move or rename a folder
scp -r /usr/test/ root@:/usr/test  # Transfer data to a remote server

Text Editing and Manipulation

bash
sed -i 's/old-word/new-word/g' *.txt  # Replace a word in a text file

System Monitoring

bash
top -u username  # Check CPU usage in Linux
df -H  # Check hard disk space
dmesg | grep ^Memory: or free -m or free  # Check RAM space
sudo dmidecode --type 17  # Display system information

---

VNC Server

bash
rpm -qa | grep vnc
rpm -q vnc-server  # Check if VNC package is available
service --status-all | grep vnc  # Check VNC server status
rpm -Uvh vnc-4_1_3-x86_linux.rpm  # Upgrade VNC server
rpm -ivh vnc-4_1_3-x86_linux.rpm  # Install VNC server
rpm -e vnc-4_1_3-x86_linux.rpm  # Uninstall VNC server
chkconfig --level 35 vncserver on  # Set VNC server to start on run levels 3 and 5
yum groupinstall "GNOME Desktop Environment"  # Install GNOME desktop environment for VNC server

---

System Information and Versions

bash
cat /etc/redhat-release  # Check Linux version
lsb_release -a  # Check Linux version
mysql> SHOW VARIABLES LIKE "%version%";  # Check MySQL version
localhost# asterisk -V  # Check Asterisk version
java -version or javac -version  # Check Java version
SQL> SELECT * FROM v$version WHERE banner LIKE 'Oracle%';  # Check Oracle version
mysql> SHOW VARIABLES LIKE 'version';  # Check MySQL version
localhost# httpd -v  # Check Apache version in Linux

Miscellaneous Commands

bash
updatedb  # Update locate command database
sjphone SIP: shortCode@SystemIP  # Make a call using SJ Phone SIP
sip:IP  # Call Asterisk using SIP

---

Tomcat Installation

bash
cd jakarta-tomcat-5.0.28
tar -zxvf tomcat.tar
cd bin
tar xvfz jsvc.tar.gz
cd jsvc-src
chmod +x configure
./configure
make
cp jsvc ..
cd ..

---

File Compression and Decompression

bash
gzip filename  # Zip a file in Linux
gunzip filename.z  # Unzip a .Z type compressed file
unzip filename.zip  # Unzip a .zip type compressed file

ens