Features:
1. The ability to restrict/control access to files
Note: 10 bits represent permissions for files (including directories)
Note: use 'ls -l' to examine permissions or GUI application like 'Nautilus'
-rwxrwxr-x 1 linuxcbt linuxcbt 681 Jan 13 11:31 regextest.pl
1st bit = file type. '-' = file, 'd' = directory
2nd - 4th bits = owner's permissions
r = read = 4
w = write = 2
x = execute = 1
- = none = 0
5th - 7th bits = group owner's permissions
r = read = 4
w = write = 2
x = execute = 1
- = none = 0
8th - 10th bits = everyone (world)
r = read = 4
w = write = 2
x = execute = 1
- = none = 0
Task:
1. Manipulate file permissions using 'chmod'
a. chmod -x regextest.pl
-rw-rw-r-- 1 linuxcbt linuxcbt 681 Jan 13 11:31 regextest.pl
rw = 6 or 4+2 for owner
rw = 6 or 4+2 for group owner
r = 4 for everyone else (world)
Octal notation: 664 for file 'regexetest.pl'
chmod 664 regextest.pl - removes execution for ALL users
chmod 775 regextest.pl - enables execution for ALL users
2. Ensure that 'regextest.pl' is rw by owner and noone else
a. chmod 600 regextest.pl
Note: File will now be rw by owner (linuxcbt) and 'root'
3. Ensure that 'regextest.pl' is r by owner and noone else
a. chmod 400 regextest.pl && ls -l regextest.pl
Note: chmod supports string values, which represent octal values
chmod +/- x file
chmod +/- w file
chmod +/- r file
chmod +/- u+x file - updates owner's execute permissions on the file
chmod +/- o+x file - updates other's execute permissions on the file
chmod +/- g+x file - updates group's execute permissions on the file
chmod a+rwx = chmod 777
chown - permits changing of ownership of files
a. chown root regextest.pl - changes ownership to 'root'
b. chown linuxcbt:sales regextest.pl - changes owner and group to 'linuxcbt:sales'
Task:
Update 'regextest.pl' so that owner and group owner may modify the file
a. chmod 660 regextest.pl
SETUID:
Features:
1. ability to execute file as owner
chmod 4760 regextest.pl - this will ensure that the perl script always executes as the user 'linuxcbt'
-rwsrw---- 1 linuxcbt sales 787 Jan 28 16:08 regextest.pl
's' in the execute position means that the program will execute as that user
SETGID:
Features:
1. Ability to enforce permissions to a directory structure
mkdir /sales
chmod 2775 /sales
Create a file in the '/sales' directory as 'linuxcbt'
seq 1000000 > linuxcbt.1million.txt
chgrp:
Permits updating of group permissions
Sticky Bit:
Features:
1. Ability to ensure that users cannot delete others' files in a directory
drwxrwxrwt 23 root root 4096 Jan 28 15:05 /tmp/
/tmp - users cannot delete other user's files in '/tmp'
chmod 3777 /sales - ensures that /sales will not lose files from incorrect users
Task:
1. Set '/sales' using sticky bit and test
a. chmod 3777 /sales && ls -ld /sales OR chmod 777 /sales && chmod +t /sales
Thursday, July 15, 2010
Monday, July 12, 2010
User/Group Management
Features:
1. The ability to control users and groups
Primary tools:
1. useradd - used to add users and modify group membership
2. system-config-users
Task:
1. Create a user named 'student1' using 'useradd'
Note: Default user settings derive from: /etc/login.defs
a. useradd student1
b. set password for user 'student1': passwd student1
Default User Accounts DB: /etc/passwd
student1:x:501:501::/home/student1:/bin/bash
username:shadow_reference:uid:gid:Description(GECOS):$HOME:$SHELL
Note: /etc/passwd is a world-readable file
Note: /etc/shadow now stores passwords in encrypted form
Note: /etc/shadow is NOT world-readable
Fields in /etc/shadow:
student1:$1$XSFMv2ru$lfTACjN.XxaxbHA0EkB4U0:13891:0:99999:7:::
1. username:
2. encrypted_password:
3. Days_since_Unix_epoch_password_was_changed (01/01/1970)
4. Days before password may be changed
5. Days after which the password MUST be changed
6. Days before password is to expire that user is warned
7. Days after password expires, that account is disabled
8. Days since Unix epoch, that account is disabled
9. Reserved field (currently unused)
2. Modify user 'student1' to have password expire after 45 days
a. usermod
Groups:
1. groupadd - adds new group
2. groups - lists groups on the system: /etc/group
/etc/group - maintains group membership information
Task: Create a 'sales' group and add 'linuxbbt' and 'student1' as members
1. groupadd sales
2. usermod -G sales linuxbbt
3. usermod -G sales student1
Note: 2 types of groups exist:
1. Primary - used by default for a user's permissions
2. Supplemental - used to determine effective permissions
Note: use 'id' to determine the group information of user
Note: Create a new shell session to realize new group membership information
userdel/groupdel are used to delete users and groups, respectively
1. The ability to control users and groups
Primary tools:
1. useradd - used to add users and modify group membership
2. system-config-users
Task:
1. Create a user named 'student1' using 'useradd'
Note: Default user settings derive from: /etc/login.defs
a. useradd student1
b. set password for user 'student1': passwd student1
Default User Accounts DB: /etc/passwd
student1:x:501:501::/home/student1:/bin/bash
username:shadow_reference:uid:gid:Description(GECOS):$HOME:$SHELL
Note: /etc/passwd is a world-readable file
Note: /etc/shadow now stores passwords in encrypted form
Note: /etc/shadow is NOT world-readable
Fields in /etc/shadow:
student1:$1$XSFMv2ru$lfTACjN.XxaxbHA0EkB4U0:13891:0:99999:7:::
1. username:
2. encrypted_password:
3. Days_since_Unix_epoch_password_was_changed (01/01/1970)
4. Days before password may be changed
5. Days after which the password MUST be changed
6. Days before password is to expire that user is warned
7. Days after password expires, that account is disabled
8. Days since Unix epoch, that account is disabled
9. Reserved field (currently unused)
2. Modify user 'student1' to have password expire after 45 days
a. usermod
Groups:
1. groupadd - adds new group
2. groups - lists groups on the system: /etc/group
/etc/group - maintains group membership information
Task: Create a 'sales' group and add 'linuxbbt' and 'student1' as members
1. groupadd sales
2. usermod -G sales linuxbbt
3. usermod -G sales student1
Note: 2 types of groups exist:
1. Primary - used by default for a user's permissions
2. Supplemental - used to determine effective permissions
Note: use 'id' to determine the group information of user
Note: Create a new shell session to realize new group membership information
userdel/groupdel are used to delete users and groups, respectively
System Utilities
Features:
1. Process listing
2. Free/available memory
3. Disk utilization
1. ps - process status/listing
a. ps -ef or ps -aux
2. top - combines, ps, uptime, free and updates regulary
3. uptime - returns useful system utilization information:
a. current time
b. uptime - days, hours and minutes
c. connected users
d. load averaged - 1,5,15 minute values
4. free - returns memory utilization
a. RAM
b. SWAP
free -m - for human readable format
5. df - returns disk partition/mount point information
a. df - returns info. using kilobytes
b. df -h - returns info. using megabytes/human readable (gigs/teray/etc.)
6. vmstat - reports on: processes, memory, paging, block I/O, traps, CPU activity
a. vmstat
b. vmstat -p /dev/hda1 - returns partitions stats for /dev/hda1 (/boot)
7. gnome-system-monitor - GUI, combining most system utilities
8. ls -ltr /proc
a. cat /proc/cpuinfo
9. kill PID - kills the process with a given PID
10. runlevel - returns runlevel information using 2 fields:
a. represents previous runlevel
b. represents current runlevel
1. Process listing
2. Free/available memory
3. Disk utilization
1. ps - process status/listing
a. ps -ef or ps -aux
2. top - combines, ps, uptime, free and updates regulary
3. uptime - returns useful system utilization information:
a. current time
b. uptime - days, hours and minutes
c. connected users
d. load averaged - 1,5,15 minute values
4. free - returns memory utilization
a. RAM
b. SWAP
free -m - for human readable format
5. df - returns disk partition/mount point information
a. df - returns info. using kilobytes
b. df -h - returns info. using megabytes/human readable (gigs/teray/etc.)
6. vmstat - reports on: processes, memory, paging, block I/O, traps, CPU activity
a. vmstat
b. vmstat -p /dev/hda1 - returns partitions stats for /dev/hda1 (/boot)
7. gnome-system-monitor - GUI, combining most system utilities
8. ls -ltr /proc
a. cat /proc/cpuinfo
9. kill PID - kills the process with a given PID
10. runlevel - returns runlevel information using 2 fields:
a. represents previous runlevel
b. represents current runlevel
Perl
Features:
1. Parses text
2. Executes programs
3. CGI - Web forms, etc.
4. Supports RegExes (Perl and POSIX)
5. etc.
Task:
1. Print 'Hello World' to STDOUT
a. perl -c helloworld.pl - checks the syntax of the script
b. perl helloworld.pl - executes the script
c. chmod +x helloworld.pl && ./helloworld.pl
2. Parse RegExes from the command line
1. Parses text
2. Executes programs
3. CGI - Web forms, etc.
4. Supports RegExes (Perl and POSIX)
5. etc.
Task:
1. Print 'Hello World' to STDOUT
a. perl -c helloworld.pl - checks the syntax of the script
b. perl helloworld.pl - executes the script
c. chmod +x helloworld.pl && ./helloworld.pl
2. Parse RegExes from the command line
Sed - Stream Editor
Features:
1. Faciliates automated text editing
2. Supports RegExes (POSIX)
3. Like Awk, supports scripting using '-F' option
4. Supports input via: STDIN, pipe, file
Usage:
1. sed [options] 'instruction[s]' file[s]
2. sed -n '1p' grep1.txt - prints the first line of the file
3. sed -n '1,5p' grep1.txt - prints the first 5 lines of the file
4. sed -n '$p' grep1.txt - prints the last line of the file
5. sed -n '1,3!p' grep1.txt - prints ALL but lines 1-3
6. sed -n '/linux/p' grep1.txt - prints lines with 'linux'
7. sed -e '/^$/d' grep1.txt - deletes blank lines from the document
8. sed -e '/^$/d' grep1.txt > sed1.txt - deletes blank lines from the document 'grep1.txt' and creates 'sed1.txt'
9. sed -ne 's/search/replace/p' sed1.txt
10. sed -ne 's/linux/unix/p' sed1.txt
11. sed -i.bak -e 's/3/4' sed1.txt - this backs up the original file and creates a new 'sed1.txt' with the modifications indicated in the command
Note: Generally, to create new files, use output redirection, instead of allowing sed to write to STDOUT
Note: Sed applies each instruction to each line
1. Faciliates automated text editing
2. Supports RegExes (POSIX)
3. Like Awk, supports scripting using '-F' option
4. Supports input via: STDIN, pipe, file
Usage:
1. sed [options] 'instruction[s]' file[s]
2. sed -n '1p' grep1.txt - prints the first line of the file
3. sed -n '1,5p' grep1.txt - prints the first 5 lines of the file
4. sed -n '$p' grep1.txt - prints the last line of the file
5. sed -n '1,3!p' grep1.txt - prints ALL but lines 1-3
6. sed -n '/linux/p' grep1.txt - prints lines with 'linux'
7. sed -e '/^$/d' grep1.txt - deletes blank lines from the document
8. sed -e '/^$/d' grep1.txt > sed1.txt - deletes blank lines from the document 'grep1.txt' and creates 'sed1.txt'
9. sed -ne 's/search/replace/p' sed1.txt
10. sed -ne 's/linux/unix/p' sed1.txt
11. sed -i.bak -e 's/3/4' sed1.txt - this backs up the original file and creates a new 'sed1.txt' with the modifications indicated in the command
Note: Generally, to create new files, use output redirection, instead of allowing sed to write to STDOUT
Note: Sed applies each instruction to each line
Awk
Features:
1. Field/Column processor
2. Supports egrep-compatible (POSIX) RegExes
3. Can return full lines like grep
4. Awk runs 3 steps:
a. BEGIN - optional
b. Body, where the main action(s) take place
c. END - optional
5. Multiple body actions can be executed by separating them using semicolons. e.g. '{ print $1; print $2 }'
6. Awk, auto-loops through input stream, regardless of the source of the stream. e.g. STDIN, Pipe, File
Usage:
1. awk '/optional_match/ { action }' file_name | Pipe
2. awk '{ print $1 }' grep1.txt
Note: Use single quotes with awk, to avoid shell interpolation of awk's variables
3. awk '{ print $1,$2 }' grep1.txt
Note: Default input and output field separators is whitespace
4. awk '/linux/ { print } ' grep1.txt - this will print ALL lines containing 'linux'
5. awk '{ if ($2 ~ /Linux/) print}' grep1.txt
6. awk '{ if ($2 ~ /8/) print }' /var/log/messages - this will print the entire line for log items for the 8th
7. awk '{ print $3 }' /var/log/messages | awk -F: '{ print $1}'
1. Field/Column processor
2. Supports egrep-compatible (POSIX) RegExes
3. Can return full lines like grep
4. Awk runs 3 steps:
a. BEGIN - optional
b. Body, where the main action(s) take place
c. END - optional
5. Multiple body actions can be executed by separating them using semicolons. e.g. '{ print $1; print $2 }'
6. Awk, auto-loops through input stream, regardless of the source of the stream. e.g. STDIN, Pipe, File
Usage:
1. awk '/optional_match/ { action }' file_name | Pipe
2. awk '{ print $1 }' grep1.txt
Note: Use single quotes with awk, to avoid shell interpolation of awk's variables
3. awk '{ print $1,$2 }' grep1.txt
Note: Default input and output field separators is whitespace
4. awk '/linux/ { print } ' grep1.txt - this will print ALL lines containing 'linux'
5. awk '{ if ($2 ~ /Linux/) print}' grep1.txt
6. awk '{ if ($2 ~ /8/) print }' /var/log/messages - this will print the entire line for log items for the 8th
7. awk '{ print $3 }' /var/log/messages | awk -F: '{ print $1}'
GREP
Features:
1. The ability to parse lines based on text and/or RegExes
2. Post-processor
3. Searches case-sensitively, by default
4. Searches for the text anywhere on the line
1. grep 'linux' grep1.txt
2. grep -i 'linux' grep1.txt - case-insensitive search
3. grep '^linux' grep1.txt - uses '^' anchor to anchor searches at the beginning of lines
4. grep -i '^linux' grep1.txt
5. grep -i 'linux$' grep1.txt - uses '$' anchor to anchor searches at the end of lines
Note: Anchors are RegEx characters (meta-characters). They're used to match at the beginning and end of lines
6. grep '[0-9]' grep1.txt - returns lines containing at least 1 number
7. grep '[a-z]' grep1.txt
8. rpm -qa | grep grep - searches the package database for programs named 'grep'
9. rpm -qa | grep -i xorg | wc -l - returns the number of pacakges with 'xorg' in their names
10. grep sshd messages
11. grep -v sshd messages - performs and inverted search (all but 'sshd' entries will be returned)
12. grep -v sshd messages | grep -v gconfd
13. grep -C 2 sshd messages - returns 2 lines, above and below matching line
Note: Most, if not all, Linux programs log linearly, which means one line after another, from the earliest to the current
Note: Use single or double quotes to specify RegExes
Also, execute 'grep' using 'egrep' when RegExes are being used
1. The ability to parse lines based on text and/or RegExes
2. Post-processor
3. Searches case-sensitively, by default
4. Searches for the text anywhere on the line
1. grep 'linux' grep1.txt
2. grep -i 'linux' grep1.txt - case-insensitive search
3. grep '^linux' grep1.txt - uses '^' anchor to anchor searches at the beginning of lines
4. grep -i '^linux' grep1.txt
5. grep -i 'linux$' grep1.txt - uses '$' anchor to anchor searches at the end of lines
Note: Anchors are RegEx characters (meta-characters). They're used to match at the beginning and end of lines
6. grep '[0-9]' grep1.txt - returns lines containing at least 1 number
7. grep '[a-z]' grep1.txt
8. rpm -qa | grep grep - searches the package database for programs named 'grep'
9. rpm -qa | grep -i xorg | wc -l - returns the number of pacakges with 'xorg' in their names
10. grep sshd messages
11. grep -v sshd messages - performs and inverted search (all but 'sshd' entries will be returned)
12. grep -v sshd messages | grep -v gconfd
13. grep -C 2 sshd messages - returns 2 lines, above and below matching line
Note: Most, if not all, Linux programs log linearly, which means one line after another, from the earliest to the current
Note: Use single or double quotes to specify RegExes
Also, execute 'grep' using 'egrep' when RegExes are being used
Tar, Gzip, Bzip2, Zip
Features:
1. Compression utilities (gzip, bzip2, zip)
2. File rollers (the ability to represent many files as one)
Gzip:
Includes:
1. gzip - compresses/decompresses files
2. gunzip - decompresses gzip files
Tasks:
1. compress '1million.txt' file using gzip
a. gzip -c 1million.txt > 1million.txt.gz
Note: gzip auto-dumps to STDOUT, by default
b. gzip -l 1million.txt.gz - returns status information
c. gunzip 1million.txt.gz - dumps to file, and removes compressed version
d. gzip -d 1million.txt.gz
e. zcat 1million.txt.gz - dumps the contents to STDOUT
f. less 1million.txt.gzip - dumps the contents of gzip files to STDOUT
Bzip2:
1. bzip2 -c 1million.txt > 1million.txt.bz2
Note: Bzip2 tends to outperform gzip on larger files
2. bunzip2 1million.txt.bz2
3. bzip2 -d 1million.txt.bz2
4. bzcat 1million.txt.bz2 - dumps contents to STDOUT
5. less 1million.txt.bz2 - also dumps the contents to STDOUT
Zip & unzip:
1. zip filename.zip path/ - general usage
2. zip 1million.txt.zip 1million.txt
Note: zip differs slight from gzip and bzip2 in that the destination file (resultant zip file) is specified before the source
3. unzip 1million.txt.zip
Tar & Gzip/Bzip2:
1. tar -cvf filename.tar path/ - creates a non-compressed archive
2. tar -cvf 1million.txt.tar 1million.txt
Note: tar, requires a small overhead for itself in each file
3. tar -czvf 1million.txt.tar.gz 1million.txt - creates, tar/gzip document
4. tar -cjvf 1million.txt.tar.bz2 1million.txt - creates, tar/bzip2 document
5. tar -tzvf
6. tar -cjvf 1million.txt.tar.bz2 1million.txt testRH5/- creates, tar/bzip2 document for the text file and 'testRH5' directory tree
1. Compression utilities (gzip, bzip2, zip)
2. File rollers (the ability to represent many files as one)
Gzip:
Includes:
1. gzip - compresses/decompresses files
2. gunzip - decompresses gzip files
Tasks:
1. compress '1million.txt' file using gzip
a. gzip -c 1million.txt > 1million.txt.gz
Note: gzip auto-dumps to STDOUT, by default
b. gzip -l 1million.txt.gz - returns status information
c. gunzip 1million.txt.gz - dumps to file, and removes compressed version
d. gzip -d 1million.txt.gz
e. zcat 1million.txt.gz - dumps the contents to STDOUT
f. less 1million.txt.gzip - dumps the contents of gzip files to STDOUT
Bzip2:
1. bzip2 -c 1million.txt > 1million.txt.bz2
Note: Bzip2 tends to outperform gzip on larger files
2. bunzip2 1million.txt.bz2
3. bzip2 -d 1million.txt.bz2
4. bzcat 1million.txt.bz2 - dumps contents to STDOUT
5. less 1million.txt.bz2 - also dumps the contents to STDOUT
Zip & unzip:
1. zip filename.zip path/ - general usage
2. zip 1million.txt.zip 1million.txt
Note: zip differs slight from gzip and bzip2 in that the destination file (resultant zip file) is specified before the source
3. unzip 1million.txt.zip
Tar & Gzip/Bzip2:
1. tar -cvf filename.tar path/ - creates a non-compressed archive
2. tar -cvf 1million.txt.tar 1million.txt
Note: tar, requires a small overhead for itself in each file
3. tar -czvf 1million.txt.tar.gz 1million.txt - creates, tar/gzip document
4. tar -cjvf 1million.txt.tar.bz2 1million.txt - creates, tar/bzip2 document
5. tar -tzvf
6. tar -cjvf 1million.txt.tar.bz2 1million.txt testRH5/- creates, tar/bzip2 document for the text file and 'testRH5' directory tree
Command Chaining
Features:
1. Permits the execution of multiple commands in sequence
2. Also permits execution based on the success or failure of a previous command
1. cat 123.txt ; ls -l - this runs first command, then second command without regards for exit status of the first command
2. cat 123.txt && ls -l - this runs second command, if first command is successful
3. cat 1234.txt && ls -l
4. cat 123.txt || ls -l - this runs second command, if first command fails
24. more|less - paginators, which display text one-page @ a time
1. more /etc/fstab
2. less 1thousand.txt
25. seq - echoes a sequence of numbers
a. seq 1000 > 1thousand.txt - creates a file with numbers 1-1000
26. su - switches users
a. su - with no options attempts to log in as 'root'
27. head - displays opening lines of text files
a. head /var/log/messages
28. tail - displays the closing lines of text files
a. tail /var/log/messages
29. wc - counts words and optionally lines of text files
a. wc -l /var/log/messages
b. wc -l 123.txt
30. file - determines file type
a. file /var/log/messages
1. Permits the execution of multiple commands in sequence
2. Also permits execution based on the success or failure of a previous command
1. cat 123.txt ; ls -l - this runs first command, then second command without regards for exit status of the first command
2. cat 123.txt && ls -l - this runs second command, if first command is successful
3. cat 1234.txt && ls -l
4. cat 123.txt || ls -l - this runs second command, if first command fails
24. more|less - paginators, which display text one-page @ a time
1. more /etc/fstab
2. less 1thousand.txt
25. seq - echoes a sequence of numbers
a. seq 1000 > 1thousand.txt - creates a file with numbers 1-1000
26. su - switches users
a. su - with no options attempts to log in as 'root'
27. head - displays opening lines of text files
a. head /var/log/messages
28. tail - displays the closing lines of text files
a. tail /var/log/messages
29. wc - counts words and optionally lines of text files
a. wc -l /var/log/messages
b. wc -l 123.txt
30. file - determines file type
a. file /var/log/messages
Linux Redirection & Pipes
Features:
1. Ability to control input and output
Input redirection '<': 1. cat < 123.txt Note: Use input redirection when program does NOT default to file as input Output redirection '>':
1. cat 123.txt > onetwothree.txt
Note: Default nature is to:
1. Clobber the target file
2. Populate with information from input stream
Append redirection '>>':
1. cat 123.txt >> numbers.txt - creates 'numbers.txt' if it doesn't exist, or appends if it does
2. cat 456.txt >> numbers.txt
Pipes '|':
Features: Connects the output stream of one command to the input stream of a subsequent command
1. cat 123.txt | sort
2. cat 456.txt 123.txt | sort
3. cat 456.txt 123.txt | sort | grep 3
1. Ability to control input and output
Input redirection '<': 1. cat < 123.txt Note: Use input redirection when program does NOT default to file as input Output redirection '>':
1. cat 123.txt > onetwothree.txt
Note: Default nature is to:
1. Clobber the target file
2. Populate with information from input stream
Append redirection '>>':
1. cat 123.txt >> numbers.txt - creates 'numbers.txt' if it doesn't exist, or appends if it does
2. cat 456.txt >> numbers.txt
Pipes '|':
Features: Connects the output stream of one command to the input stream of a subsequent command
1. cat 123.txt | sort
2. cat 456.txt 123.txt | sort
3. cat 456.txt 123.txt | sort | grep 3
BASIC LINUX COMMANDS
1. tty - reveals the current terminal
2. whoami - reveals the currently logged-in user
3. which - reveals where in the search path a program is located
4. echo - prints to the screen
a. echo $PATH - dumps the current path to STDOUT
b. echo $PWD - dumps ths contents of the $PWD variable
c. echo $OLDPWD - dumps the most recently visited directory
5. set - prints and optionally sets shell variables
6. clear - clears the screen or terminal
7. reset - resets the screen buffer
8. history - reveals your command history
a. !690 - executes the 690th command in our history
b. command history is maintained on a per-user basis via:
~/.bash_history
~ = users's $HOME directory in the BASH shell
9. pwd - prints the working directory
10. cd - changes directory to desired directory
a. 'cd ' with no options changes to the $HOME directory
b. 'cd ~' changes to the $HOME directory
c. 'cd /' changes to the root of the file system
d. 'cd Desktop/' changes us to the relative directory 'Desktop'
e. 'cd ..' changes us one-level up in the directory tree
f. 'cd ../..' changes us two-levels up in the directory tree
11. Arrow keys (up and down) navigates through your command history
12. BASH supports tab completion:
a. type unique characters in the command and press 'Tab' key
13. You can copy and paste in GNOME terminal windows using:
a. left button to block
b. right button to paste OR Ctrl-Shift-v to paste
14. ls - lists files and directories
a. ls / - lists the contents of the '/' mount point
b. ls -l - lists the contents of a directory in long format:
Includes: permissions, links, ownership, size, date, name
c. ls -ld /etc - lists properties of the directory '/etc', NOT the contents of '/etc'
d. ls -ltr - sorts chronologically from older to newer (bottom)
e. ls --help - returns possible usage information
f. ls -a - reveals hidden files. e.g. '.bash_history'
Note: files/directories prefixed with '.' are hidden. e.g. '.bash_history'
15. cat - catenates files
a. cat 123.txt - dumps the contents of '123.txt' to STDOUT
b. cat 123.txt 456.txt dumps both files to STDOUT
c. cat 123.txt 456.txt > 123456.txt - creates new catenated file
16. mkdir - creates a new directory
a. mkdir testRH5 - creates a 'testRH5' directory
17. cp - copies files
a. cp 123.txt testRH5/
By default, 'cp' does NOT preserve the original modification time
b. cp -v 456.txt testRH5/
18. mv - moves files
a. mv 123456.txt testRH5/ - moves the file, preserving timestamp
19. rm - removes files/directories
a. rm 123.txt
b. rm -rf 456.txt - removes recursively and enforces
20. touch - creates blank file/updates timestamp
a. touch test.txt - will create a zero-byte file, if it doesn't exist
b. touch 123456.txt - will update the timestamp
c. touch -t 200801091530 123456.txt - changes timestamp
21. stat - reveals statistics of files
a. stat 123456.txt - reveals full attributes of the file
22. find - finds files using search patterns
a. find / -name 'fstab'
Note: 'find' can search for fields returned by the 'stat' command
23. alias - returns/sets aliases for commands
a. alias - dumps current aliases
b. alias copy='cp -v'
2. whoami - reveals the currently logged-in user
3. which - reveals where in the search path a program is located
4. echo - prints to the screen
a. echo $PATH - dumps the current path to STDOUT
b. echo $PWD - dumps ths contents of the $PWD variable
c. echo $OLDPWD - dumps the most recently visited directory
5. set - prints and optionally sets shell variables
6. clear - clears the screen or terminal
7. reset - resets the screen buffer
8. history - reveals your command history
a. !690 - executes the 690th command in our history
b. command history is maintained on a per-user basis via:
~/.bash_history
~ = users's $HOME directory in the BASH shell
9. pwd - prints the working directory
10. cd - changes directory to desired directory
a. 'cd ' with no options changes to the $HOME directory
b. 'cd ~' changes to the $HOME directory
c. 'cd /' changes to the root of the file system
d. 'cd Desktop/' changes us to the relative directory 'Desktop'
e. 'cd ..' changes us one-level up in the directory tree
f. 'cd ../..' changes us two-levels up in the directory tree
11. Arrow keys (up and down) navigates through your command history
12. BASH supports tab completion:
a. type unique characters in the command and press 'Tab' key
13. You can copy and paste in GNOME terminal windows using:
a. left button to block
b. right button to paste OR Ctrl-Shift-v to paste
14. ls - lists files and directories
a. ls / - lists the contents of the '/' mount point
b. ls -l - lists the contents of a directory in long format:
Includes: permissions, links, ownership, size, date, name
c. ls -ld /etc - lists properties of the directory '/etc', NOT the contents of '/etc'
d. ls -ltr - sorts chronologically from older to newer (bottom)
e. ls --help - returns possible usage information
f. ls -a - reveals hidden files. e.g. '.bash_history'
Note: files/directories prefixed with '.' are hidden. e.g. '.bash_history'
15. cat - catenates files
a. cat 123.txt - dumps the contents of '123.txt' to STDOUT
b. cat 123.txt 456.txt dumps both files to STDOUT
c. cat 123.txt 456.txt > 123456.txt - creates new catenated file
16. mkdir - creates a new directory
a. mkdir testRH5 - creates a 'testRH5' directory
17. cp - copies files
a. cp 123.txt testRH5/
By default, 'cp' does NOT preserve the original modification time
b. cp -v 456.txt testRH5/
18. mv - moves files
a. mv 123456.txt testRH5/ - moves the file, preserving timestamp
19. rm - removes files/directories
a. rm 123.txt
b. rm -rf 456.txt - removes recursively and enforces
20. touch - creates blank file/updates timestamp
a. touch test.txt - will create a zero-byte file, if it doesn't exist
b. touch 123456.txt - will update the timestamp
c. touch -t 200801091530 123456.txt - changes timestamp
21. stat - reveals statistics of files
a. stat 123456.txt - reveals full attributes of the file
22. find - finds files using search patterns
a. find / -name 'fstab'
Note: 'find' can search for fields returned by the 'stat' command
23. alias - returns/sets aliases for commands
a. alias - dumps current aliases
b. alias copy='cp -v'
FTP INSTALLATION OF REDHAT LINUX 5
Steps:
1. Create FTP user account on FTP server
a. 'useradd -s /bin/false -d /srv/wwwlinux.com linuxinstall'
b. 'passwd linuxinstall'
2. Confirm FTP connectivity as the user 'linuxinstall'
3. Reboot server with 'boot.iso' CD and type 'linux askmethod'
1. Create FTP user account on FTP server
a. 'useradd -s /bin/false -d /srv/wwwlinux.com linuxinstall'
b. 'passwd linuxinstall'
2. Confirm FTP connectivity as the user 'linuxinstall'
3. Reboot server with 'boot.iso' CD and type 'linux askmethod'
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