Showing posts with label linux. Show all posts
Showing posts with label linux. Show all posts
Tuesday 16 October 2012
Practical ls Command Examples For Fun & Profit
The power of linux lies in the shell through which we can perform complex job in no time. While the directory listing command 'ls' seems to be very simple command, the linux shell provides the power to use switches and pipes to do anything from terminal. Check out this list with practically useful examples using ls.
Any more example that fires up in your mind? Feel free to share over here ;)
Read more...
Display all files including hidden files/folders
ls -a
Display one file/folder per line
ls -1
Count number of files & folders
ls -1 | wc -l
Human readable file sizes (eg. Mb or Gb)
ls -lh
Alphabetically sort the listing
ls -X
Only list the folders in current directory
ls -d */
ls -p | grep /
ls -p | grep /
Display folders in current directory consisting certain patterns
ls -l D* | grep :$
ls -l *a* | grep :$
ls -l *a* | grep :$
List files by descending order of modification time
ls -lt
ls -l --sort=time #alternative long version
ls -l --sort=time #alternative long version
List files by descending order of creation time
ls -lct
List files in reverse order
ls -ltr
ls -l --sort=time --reverse #alternative long version
ls -l --sort=time --reverse #alternative long version
List files in descending order of file size
ls -lSh
ls -lh --sort=size
ls -lSh1 *.avi #find largest AVI file
rm `ls -S1 | head -1` #delete largest file in current folder
ls -lh --sort=size
ls -lSh1 *.avi #find largest AVI file
rm `ls -S1 | head -1` #delete largest file in current folder
List files in ascending order of file size
ls -lShr
ls -lh --sort=size --reverse #alternative long version
ls -lh --sort=size --reverse #alternative long version
Display directories in recursive manner
ls -R
Display the files/folders created today
ls -l --time-style=+%F | grep `date +%F`
Display the files/folders created this year
ls -l --time-style=+%y | grep `date +%y`
Any more example that fires up in your mind? Feel free to share over here ;)
Read more...
Practical ls Command Examples For Fun & Profit
2012-10-16T00:44:00+05:45
Cool Samar
command line|edubuntu|fedora|linux|ubuntu|ubuntu 12.04|ubuntu 12.10|
Comments
Labels:
command line,
edubuntu,
fedora,
linux,
ubuntu,
ubuntu 12.04,
ubuntu 12.10
Bookmark this post:blogger tutorials
Social Bookmarking Blogger Widget |
Monday 15 October 2012
Useful Nautilus Shortcuts
Nautilus is a default file manager for GNOME Desktop and is used as the default file manager in several linux distros such as Ubuntu. I love nautilus because its simple, friendly, and clean, supports local as well as remote file systems over different protocols. Moreover, there are several useful shortcuts that make life easier while using nautilus.
Below is the list of the most helpful shortcuts for navigation and file management in the nautilus:
Ctrl + r: Refresh the current view
Ctrl + h: Toggle show/hide mode for hidden files
F9: Show/Hide the side pane
Ctrl + l: Activate location/url bar (You can then provide path to local or remote filesystems or quickly copy the absolute paths)
Alt + Up Arrow: Move up one directory level
Alt + Down Arrow: Move down one directory level (the directory to be entered should be selected for this to work)
Alt + Left Arrow: Go back to the previous folder in view
Alt + Right Arrow: Go forward
Ctrl + Shift + n: Create a new empty directory
Ctrl + (+ / -): Zoom in (+) or zoom out (-)
Ctrl + 0: Zoom to normal state
Alt + Enter: View selected file/folder properties
F2: Rename selected file/folder
Ctrl + Shift + Drag file/folder: Create symbolic link to file/folder
Ctrl + f: Search for files/folders
Ctrl + s: Select files based upon templates (eg. select all pdf files using *.pdf)
Ctrl + 1: Toggle view as icons
Ctrl + 2: Toggle view as lists
Ctrl + 3: Toggle compact view
Ctrl + w: Close current nautilus window
Ctrl + Shift + w: Current all open nautilus windows
Ctrl + T: Open new tab
Alt + HOME: Navigate to HOME folder
F6: Toggle between side pane and central pane
Know more shortcuts? Share as the comments :)
Read more...
Below is the list of the most helpful shortcuts for navigation and file management in the nautilus:
Ctrl + r: Refresh the current view
Ctrl + h: Toggle show/hide mode for hidden files
F9: Show/Hide the side pane
Ctrl + l: Activate location/url bar (You can then provide path to local or remote filesystems or quickly copy the absolute paths)
Alt + Up Arrow: Move up one directory level
Alt + Down Arrow: Move down one directory level (the directory to be entered should be selected for this to work)
Alt + Left Arrow: Go back to the previous folder in view
Alt + Right Arrow: Go forward
Ctrl + Shift + n: Create a new empty directory
Ctrl + (+ / -): Zoom in (+) or zoom out (-)
Ctrl + 0: Zoom to normal state
Alt + Enter: View selected file/folder properties
F2: Rename selected file/folder
Ctrl + Shift + Drag file/folder: Create symbolic link to file/folder
Ctrl + f: Search for files/folders
Ctrl + s: Select files based upon templates (eg. select all pdf files using *.pdf)
Ctrl + 1: Toggle view as icons
Ctrl + 2: Toggle view as lists
Ctrl + 3: Toggle compact view
Ctrl + w: Close current nautilus window
Ctrl + Shift + w: Current all open nautilus windows
Ctrl + T: Open new tab
Alt + HOME: Navigate to HOME folder
F6: Toggle between side pane and central pane
Know more shortcuts? Share as the comments :)
Read more...
Useful Nautilus Shortcuts
2012-10-15T17:51:00+05:45
Cool Samar
keyboard shortcuts|linux|nautilus|tricks and tips|ubuntu|
Comments
Labels:
keyboard shortcuts,
linux,
nautilus,
tricks and tips,
ubuntu
Bookmark this post:blogger tutorials
Social Bookmarking Blogger Widget |
Saturday 13 October 2012
How To Exclude Directory While Compressing With Tar
Quite a handy and useful tip here. Several times, you want to compress files and folders but there might be cases when you want to compress your data excluding some of the directories. Tar command makes the process easier by providing us a exclusion switch.
I was actually backing up data I had downloaded in the remote server and wanted a copy of backup tar file in my system as well. But all those images that resided in the folders deep inside were not necessary for me. So all I did was something like below:
The above command effectively excludes all the sub directories from testdirectory having the string image (eg. image, images, images_old in my case) and creates the backup.tar file. Moreover, the --exclude switch also co-operates the regular expressions so you can specify the regex to filter the directories. As an example, the command below excludes the directories a, b, c, d, and e while creating the tarball.
You can exploit this switch for ease several times in your daily works. I hope this helps :)
Read more...
I was actually backing up data I had downloaded in the remote server and wanted a copy of backup tar file in my system as well. But all those images that resided in the folders deep inside were not necessary for me. So all I did was something like below:
adm@RServ:~$ tar cvf backup.tar test --exclude=image*
The above command effectively excludes all the sub directories from testdirectory having the string image (eg. image, images, images_old in my case) and creates the backup.tar file. Moreover, the --exclude switch also co-operates the regular expressions so you can specify the regex to filter the directories. As an example, the command below excludes the directories a, b, c, d, and e while creating the tarball.
adm@RServ:~$ tar cvf backup.tar test --exclude=[a-e]
You can exploit this switch for ease several times in your daily works. I hope this helps :)
Read more...
How To Exclude Directory While Compressing With Tar
2012-10-13T19:32:00+05:45
Cool Samar
command line|linux|tricks and tips|
Comments
Labels:
command line,
linux,
tricks and tips
Bookmark this post:blogger tutorials
Social Bookmarking Blogger Widget |
Tuesday 2 October 2012
Binary, Hex, Octal and Decimal Conversion Under Linux
Base conversions are easy with linux CLI. No need of fancy GUI-based calculator to perform base conversions when there is our favorite linux terminal.
We will be using bc, a calculator language that supports arbitrary precision numbers with interactive execution of statements. We will exploit the pipelining feature of shell and will let the bc process our query to convert the numbers from one base to other.
As seen in all the examples above, the conversion to decimal numbers does not require you to specify the obase as obase defaults to decimal. The same thing applies for ibase i.e. ibase defaults to decimal base by default as seen in the examples below.
Now lets try some conversion with decimal numbers as the input base.
Below are few more examples of base conversions to clarify the use of the command.
I hope this is helpful ;-)
Read more...
We will be using bc, a calculator language that supports arbitrary precision numbers with interactive execution of statements. We will exploit the pipelining feature of shell and will let the bc process our query to convert the numbers from one base to other.
From binary to decimal
The syntax is obvious and we will follow the similar syntax for all the conversions. In this first example, we are converting the binary number 1101101 from input base binary to decimal(obase defaults to decimal unless specified).
samar@samar-Techgaun:~$ echo "ibase=2;1101101" | bc
109
109
From octal to decimal
samar@samar-Techgaun:~$ echo "ibase=8;1101101" | bc
295489
295489
From Hexadecimal to decimal
samar@samar-Techgaun:~$ echo "ibase=16;A1F3DF" | bc
10613727
10613727
From N-base to decimal
All you need to do is provide the appropriate ibase value (eg. ibase=4 for 4-base to decimal conversion).
samar@samar-Techgaun:~$ echo "ibase=16;A1F3DF" | bc
10613727
10613727
As seen in all the examples above, the conversion to decimal numbers does not require you to specify the obase as obase defaults to decimal. The same thing applies for ibase i.e. ibase defaults to decimal base by default as seen in the examples below.
Now lets try some conversion with decimal numbers as the input base.
From decimal to binary
samar@samar-Techgaun:~$ echo "obase=2;109" | bc
1101101
1101101
From decimal to octal
samar@samar-Techgaun:~$ echo "obase=8;295489" | bc
1101101
1101101
From decimal to hexadecimal
samar@samar-Techgaun:~$ echo "obase=16;10613727" | bc
A1F3DF
A1F3DF
From decimal to N-base
All you need to do is provide the appropriate obase value (eg. obase=4 for decimal to 4-base conversion).
samar@samar-Techgaun:~$ echo "obase=4;121" | bc
1321
1321
Below are few more examples of base conversions to clarify the use of the command.
From binary to octal
samar@samar-Techgaun:~$ echo "ibase=2;obase=8;1111" | bc
17
17
From hexadecimal to binary
samar@samar-Techgaun:~$ echo "ibase=16;obase=2;AFBE" | bc
1010111110111110
1010111110111110
I hope this is helpful ;-)
Read more...
Binary, Hex, Octal and Decimal Conversion Under Linux
2012-10-02T22:12:00+05:45
Cool Samar
command line|linux|mathematics|tricks and tips|ubuntu|
Comments
Labels:
command line,
linux,
mathematics,
tricks and tips,
ubuntu
Bookmark this post:blogger tutorials
Social Bookmarking Blogger Widget |
Friday 14 September 2012
How To Find The Location Of Command In Linux
Sometimes you need to find the pathnames or locations of commands you use frequently. In this post, I am going to discuss two useful commands that are useful for locating Linux commands.
The first command to locate the Linux commands is which. This command returns the pathnames of the files or links. However, it does not follow the symbolic links.
You can also find the pathnames of multiple commands at once using which command.
The other command is type command which is useful to determine if a command is an alias, a built-in command or an independent command.
You can play more with the type command. I hope this helps :)
Read more...
The first command to locate the Linux commands is which. This command returns the pathnames of the files or links. However, it does not follow the symbolic links.
samar@Techgaun:~$ which bash
/bin/bash
/bin/bash
You can also find the pathnames of multiple commands at once using which command.
samar@Techgaun:~$ which -a bash cat ls iftop
/bin/bash
/bin/cat
/bin/ls
/usr/sbin/iftop
/bin/bash
/bin/cat
/bin/ls
/usr/sbin/iftop
The other command is type command which is useful to determine if a command is an alias, a built-in command or an independent command.
samar@Techgaun:~$ type gedit
gedit is /usr/bin/gedit
samar@Techgaun:~$ type grep
grep is aliased to `grep --color=auto'
samar@Techgaun:~$ type -t iftop
file
gedit is /usr/bin/gedit
samar@Techgaun:~$ type grep
grep is aliased to `grep --color=auto'
samar@Techgaun:~$ type -t iftop
file
You can play more with the type command. I hope this helps :)
Read more...
How To Find The Location Of Command In Linux
2012-09-14T01:05:00+05:45
Cool Samar
command line|linux|ubuntu|
Comments
Labels:
command line,
linux,
ubuntu
Bookmark this post:blogger tutorials
Social Bookmarking Blogger Widget |
Monday 3 September 2012
Preventing Accidental Overwriting Of Files In Bash Shell
How many times has this happened to you? It used to happen once in a while with me. A Linux user learns to use the redirection operators such as '>' and '>>' but accidental overwriting starts to become common in commands you use and shell scripts you write.
The accidental overwriting of files that happens unintentionally is known as clobbering and it commonly happens while using the '>' redirection operator.
In the above example, the mycmd clobbers any existing data in the myfile file if that file exists already. Worse things may happen sometime. Imagine accidentally typing
instead of possibly using other redirection operators (like >> or <). Thankfully, you could recover /etc/passwd from either /etc/passwd- or /var/backups/passwd.bak if you hadn't rm'd these files.
To prevent such accidental overwriting, we can set the noclobber environment variable. Below is a session of enabling this variable:
As seen above, you have to turn on the noclobber variable using the set -o noclobber command in your shell. However, you might want to intentionally overwrite contents of certain files even when the noclobber is turned on.
Notice the >| in place of your normal > redirection operator. Using this operator, you can however overwrite the existing files even if the noclobber is turned on.
If you want to turn off the noclobber variable, type the following:
You can also permanently turn on the noclobber by the following command:
Moreover, such accidental overwriting can be prevented by enabling the interactive mode which is available in most of the linux commands. For example, you can write the alias for many commands that are likely to cause accidental overwriting. See some examples of aliases below:
You could even keep these aliases in your ~/.bashrc file permanently. Enabling such interactive modes by default in the commands that are more likely to cause accidental overwriting can prevent clobbering in many cases.
I hope this proves useful to you :)
Read more...
The accidental overwriting of files that happens unintentionally is known as clobbering and it commonly happens while using the '>' redirection operator.
samar@Techgaun:~$ mycmd > myfile
In the above example, the mycmd clobbers any existing data in the myfile file if that file exists already. Worse things may happen sometime. Imagine accidentally typing
samar@Techgaun:~$ mycmd > /etc/passwd
instead of possibly using other redirection operators (like >> or <). Thankfully, you could recover /etc/passwd from either /etc/passwd- or /var/backups/passwd.bak if you hadn't rm'd these files.
To prevent such accidental overwriting, we can set the noclobber environment variable. Below is a session of enabling this variable:
samar@Techgaun:~/Desktop/test$ echo "www.techgaun.com" > myfile
samar@Techgaun:~/Desktop/test$ echo "Overwriting techgaun.com" > myfile
samar@Techgaun:~/Desktop/test$ set -o noclobber
samar@Techgaun:~/Desktop/test$ echo "Retrying to overwrite" > myfile
-bash: myfile: cannot overwrite existing file
samar@Techgaun:~/Desktop/test$ echo "Overwriting techgaun.com" > myfile
samar@Techgaun:~/Desktop/test$ set -o noclobber
samar@Techgaun:~/Desktop/test$ echo "Retrying to overwrite" > myfile
-bash: myfile: cannot overwrite existing file
As seen above, you have to turn on the noclobber variable using the set -o noclobber command in your shell. However, you might want to intentionally overwrite contents of certain files even when the noclobber is turned on.
samar@Techgaun:~$ mycmd >| myfile
Notice the >| in place of your normal > redirection operator. Using this operator, you can however overwrite the existing files even if the noclobber is turned on.
If you want to turn off the noclobber variable, type the following:
samar@Techgaun:~$ set +o noclobber
You can also permanently turn on the noclobber by the following command:
samar@Techgaun:~$ echo "set -o noclobber" >> ~/.bashrc
Moreover, such accidental overwriting can be prevented by enabling the interactive mode which is available in most of the linux commands. For example, you can write the alias for many commands that are likely to cause accidental overwriting. See some examples of aliases below:
samar@Techgaun:~$ alias rm=rm -i
samar@Techgaun:~$ alias mv=mv -i
samar@Techgaun:~$ alias mv=mv -i
You could even keep these aliases in your ~/.bashrc file permanently. Enabling such interactive modes by default in the commands that are more likely to cause accidental overwriting can prevent clobbering in many cases.
I hope this proves useful to you :)
Read more...
Preventing Accidental Overwriting Of Files In Bash Shell
2012-09-03T22:56:00+05:45
Cool Samar
bash|command line|fedora|filesystem|linux|ubuntu|ubuntu 11.10|
Comments
Labels:
bash,
command line,
fedora,
filesystem,
linux,
ubuntu,
ubuntu 11.10
Bookmark this post:blogger tutorials
Social Bookmarking Blogger Widget |
Sunday 2 September 2012
How To Search Manual Pages In Linux
Linux system consists of hundreds of binaries, several syscalls, and other stuffs that do have manual page. What if you want to locate or find the commands by searching through the manual pages? In this post, I am going to talk about one such useful command to search through the manual page names and short descriptions.
The command I am talking about is the apropos command. The best way to learn any linux command is to read its corresponding manual and go through the help (-h or --help) so lets poke through the help of apropos itself.
Particularly, the -e switch is quite useful to filter out your search. See the example below:
Each command has its associated short description and the apropos command searches the short description section of appropriate manual page for the provided keyword. You can also specify the search keywords in the form of regular expression for more flexibility. I hope this command counts as useful one :)
Read more...
The command I am talking about is the apropos command. The best way to learn any linux command is to read its corresponding manual and go through the help (-h or --help) so lets poke through the help of apropos itself.
samar@Techgaun:~$ apropos -h Usage: apropos [OPTION...] KEYWORD... -d, --debug emit debugging messages -v, --verbose print verbose warning messages -e, --exact search each keyword for exact match -r, --regex interpret each keyword as a regex -w, --wildcard the keyword(s) contain wildcards -a, --and require all keywords to match -l, --long do not trim output to terminal width -C, --config-file=FILE use this user configuration file -L, --locale=LOCALE define the locale for this search -m, --systems=SYSTEM use manual pages from other systems -M, --manpath=PATH set search path for manual pages to PATH -s, --section=SECTION search only this section -?, --help give this help list --usage give a short usage message -V, --version print program version Mandatory or optional arguments to long options are also mandatory or optional for any corresponding short options. The --regex option is enabled by default. Report bugs to cjwatson@debian.org.
Particularly, the -e switch is quite useful to filter out your search. See the example below:
samar@Techgaun:~$ apropos -e tar bf_tar (1) - shell script to write a tar file of a bogofilter direc... bf_tar-bdb (1) - shell script to write a tar file of a bogofilter direc... git-tar-tree (1) - Create a tar archive of the files in the named tree ob... lz (1) - gunzips and shows a listing of a gzip'd tar'd archive mxtar (1) - Wrapper for using GNU tar directly from a floppy disk ptar (1) - a tar-like program written in perl tar (1) - The GNU version of the tar archiving utility tar (5) - format of tape archive files tgz (1) - makes a gzip'd tar archive uz (1) - gunzips and extracts a gzip'd tar'd archive
Each command has its associated short description and the apropos command searches the short description section of appropriate manual page for the provided keyword. You can also specify the search keywords in the form of regular expression for more flexibility. I hope this command counts as useful one :)
Read more...
How To Search Manual Pages In Linux
2012-09-02T02:07:00+05:45
Cool Samar
command line|edubuntu|fedora|linux|tricks and tips|ubuntu|
Comments
Labels:
command line,
edubuntu,
fedora,
linux,
tricks and tips,
ubuntu
Bookmark this post:blogger tutorials
Social Bookmarking Blogger Widget |
Saturday 1 September 2012
Access Linux Filesystems In Windows Using Linux Reader
Earlier today, I had to access my HDD in Windows 7 through USB bridge which I had been using as an internal hard disk for my laptop but unfortunately it didn't. A quick googling revealed a very useful tool by Diskinternals.
Linux Reader is a free software from Diskinternals which excel in building recovery software solutions. Linux reader supports several filesystems used by Linux OS. Below is the list of supported filesystems:
The program provides for read-only access and does not allow you to make records in file system partitions. This guarantees that the interference in an alterative file system will not affect the work of Linux later. Apart from this, it is necessary to note, that it gives you an opportunity to use common Windows Explorer for extracting data. A preview option for pictures is one more pleasant point, which is worth mentioning. While saving, it ignores file security policies. It means that it is possible to access absolutely any file on a Linux disk from Windows.
More details on Diskinternal's site
Download Linux Reader
Read more...
Linux Reader is a free software from Diskinternals which excel in building recovery software solutions. Linux reader supports several filesystems used by Linux OS. Below is the list of supported filesystems:
- Ext2/3/4
- ReiserFS, Reiser4
- HFS, HFS+
- FAT, exFAT
- NTFS, ReFS
- UFS2
The program provides for read-only access and does not allow you to make records in file system partitions. This guarantees that the interference in an alterative file system will not affect the work of Linux later. Apart from this, it is necessary to note, that it gives you an opportunity to use common Windows Explorer for extracting data. A preview option for pictures is one more pleasant point, which is worth mentioning. While saving, it ignores file security policies. It means that it is possible to access absolutely any file on a Linux disk from Windows.
More details on Diskinternal's site
Download Linux Reader
Read more...
Access Linux Filesystems In Windows Using Linux Reader
2012-09-01T18:08:00+05:45
Cool Samar
filesystem|linux|windows|
Comments
Labels:
filesystem,
linux,
windows
Bookmark this post:blogger tutorials
Social Bookmarking Blogger Widget |
Subscribe to:
Posts (Atom)