Skip to main content

Information Commands

apropos subject shows commands related to subject (ex: apropos floppy)
If it never finds anything, update db with “mandb”as root.
cal displays a calendar (ex: “cal 2004” to see all of 2004)
date prints or the system’s date and time
lists the amount of diskspace used and available. Putting “.”
after the command lists the diskspace on the partition you are
using right then. Use –h to convert bytes to KB, MB, GB.
dmesg quick view of the boot log from the last system boot
du gives the amount of diskspace taken by the directory. Try -h
free gives the amount of memory available
history displays the last commands that you issued at the prompt
hostname prints the name of the machine used
id prints information about the user/owner of shell
info command similar to the man command but with hyperlinking available
last username displays information about previous logins of username
ldd program lists the shared libraries required by program
lsattr file lists the file attributes of a given file
lsmod lists all loaded kernel modules
lspci lists all PCI devices
lsusb lists all USB devices
man -k command gives more information about different commands. -k gives
the manuals that contain information about the keyword
ps lists the active processes running in your account (try “ps -ef”)
rpm –q program tells you whether program is installed or not (and version)
sdiff file1 file2 compares file1 to file2 and prints the lines that differ
stty shows and sets terminal characteristics
top displays in real-time a list of running tasks
tty prints the tty of a shell
uname displays information about the operating system
uptime displays the uptime of the machine and the load it carries
whatis command summary of command (run makewhatis to build DB)
whoami (sometimes “who am i”) gives your username, tty and time the shell was started

xwininfo print information on the window you click (X-Windows only)


Popular posts from this blog

KTU-FOSS LAB Solutions

Write shell scripts to show the following  ( you can write menu driven programs)
 Currently logged user and his logname ( logname)  Your current shell ( echo $SHELL)  Your home directory ( echo $HOME)  Your operating system type (echo $OSTYPE)  Your current path setting ( echo $PATH)  Your current working directory ( echo $PWD )  Show Currently logged  users ( w or who -H)      Show only the user name of logged users in the host ( users)      Details of last login ( last cek....where cek is the user id )  About your OS and version, release number, kernel version ( uname -a or  cat  /proc/version)  Show all available shells ( cat /etc/shells )  Show mouse settings (cat  /sys/class/input/mouse*/device/name )  Show computer CPU information       CPU details      ( cat /proc/cpuinfo | more )       Show information on  CPU architecture ( lscpu)       Number of Processor core ( nproc)  Show memory information       Memory details ( cat /proc/meminfo | more )       Display file system disk usage ( d…

Important Directories and Files

Important Directories
/bin                            holds the “essential” Linux commands and utilities /boot                          holds files required for boot process (kernel, vmlinuz, grub) /dev                            holds device files (hard drive, USB, CD-ROM, etc.) /etc                             holds system configuration files /etc/init.d                    holds scripts to start/stop network services /etc/rc.d                     holds system startup/shutdown scripts /etc/X11                      holds configuration files for X-windows /home                        holds user home directories (except for the root account) /lib                               holds system/shared library files /lost+found                holds files restored after system crash /mnt                            used as temporary mount point for CD-ROM, floppy, etc. /opt                              typically where large software applications are installed /proc                           holds kerne…

ER Diagrams to Table

REDUCING E-R DIAGRAM TO TABLE - A database which conforms to an E R diagram can be represented by collection of tables .For each entity set and for each relationship set in the database, we will create unique tables, which is assigned the name of the corresponding entity set or relationship sets . Each table has a no. of columns which have unique names. Each row in the table corresponds to an entity or a relationship.

REPRESENTATION OF STRONG ENTITY SET -Let E be a strong entity set with descriptive attributes a1, a2....aN . We represent this entity by table called E with N distinct columns, each of which corresponds to one of the attributes of E.

REPRESENTATION OF RELATIONSHIP SET - Let R be a relation ship set involving entity set E1,E2....En Let attribute(R) consists of 'm' attributes We can represent this relation ship set by a table called R with m distinct columns, each of which corresponds to one of the attributes in attribute (R) plus the primary key of E1..En.