Handy bash commands for finding out stuff in Linux:
# 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
An article: Tips for Optimizing Linux Memory

# 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

Look at man <command> or info <command> for the flags I used and for other options you can use for bash commands.
Source: http://www.linuxquestions.org/questions/linux-general-1/command-to-check-hardware-135433/

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uname-Linux Command

   

uname

 

Print system information, print information about the machine    and operating system it is run on. If no options are given, `uname' acts as  if the `-s' option were given.

SYNTAX
      uname [options]...

OPTIONS

`-a'
`--all'
     Print all of the below information.

`-m'
`--machine'
     Print the machine (hardware) type.

`-n'
`--nodename'
     Print the machine's network node hostname.

`-p'
`--processor'
     Print the machine's processor type

`-r'
`--release'
     Print the operating system release.

`-s'
`--sysname'
     Print the operating system name.

`-v'
     Print the operating system version.

If multiple options or `-a' are given, the selected information    is printed in this order:
 
  SYSNAME NODENAME RELEASE OSVERSION MACHINE
 
  The OSVERSION, at least, may well be multiple words.
  For example:
  uname -a
  => Linux hayley 1.0.4 #3 Thu May 12 18:06:34 1994 i486

Related Linux Bash commands:
 
  env - Display, set, or remove    environment variables
  groups - Print group names a user is in
  hostname - Print or set system name
  id - Print user and group id's
  logname - Print current login name
  ps - list processes
  tty - Print filename of terminal on stdin
  users - Print login names of users currently logged    in
  who - Print who is currently logged in
  whoami - Print the current user id and name (`id -un')