Commands to check the hardware details and essential commands

Find CPU specifications
cat /proc/cpuinfo

# Find running kernel version
uname -r

# What compiler version do I have installed
gcc -v
gcc --version

# What is the running kernel and compiler installed
cat /proc/version

# Find X server version
X -showconfig

# What pci cards are installed and what irq/port is used
cat /proc/pci

# What kernel modules are loaded
lsmod

# Memory and swap information
cat /proc/meminfo
free


# How are the hard drives partitioned
fdisk -l

# How much free/used drive space
df -h

# Show disk usage by current directory and all subdirectories
du | less

# What takes up so much space on your box
# Run from the directory in question and the largest chunk shows up last
find $1 -type d | xargs du -sm | sort -g

# What is the distribution
cat /etc/.product
cat /etc/.issue
cat /etc/issue
cat /etc/issue.net
sysinfo

# For finding or locating files
find
locate
which
whereis

# Use dmesg to view the kernel ring buffer (error messages)
dmesg | less

# Watch error messages as they happen (sysklog needed)
as root, tail -f /var/log/messages (shows last 10 lines, use a number in front of f for more lines)

# What processes are running
ps -A

# Find a process by name
ps -ef | grep -i <plain text>
For example, XCDroast
ps -ef xcdroast

# See current environment list, or pipe to file
env | more
env > environmentvariablelist.txt

# Show current userid and assigned groups
id

# See all command aliases for the current user
alias

# See rpms installed on current system
rpmquery --all | less
rpmquery --all > <filename>
rpmquery --all | grep -i <plaintext>

Autospec for tarballs
RPM tools

# What directory am I using
pwd

# Get ls colors in less
ls --color=always | less -R
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smartctl -d ata -a /dev/sda
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semanage port -l | grep ssh - to check & change the port number you can use this, there are various options with the semanage where you can substitue the folder name with the contents /home1 /home  eg: semange fcontext -a -e /home1 /home
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    at 3am sunday

Once you hit the Enter button, the command prompt will open to ask for input. Simply enter “reboot” as shown below:

    at> reboot

Lastly, in order to save the settings, press “CTRL+D”.

The “at” command could be used to schedule any task which you want to run once. In order to know more about the “at” command enter “man at” through your command line interface.