Showing posts with label Unix Less Command. Show all posts
Showing posts with label Unix Less Command. Show all posts

Different File Types Open & View with Linux Less Command

Posted by Admin on Monday, July 7, 2014 / Labels: / Comments: (0)
In this article, let us review how Linux less command can be used to open and view the following 10 different file types:
  1. PDF File – *.pdf
  2. Word Document- *.doc
  3. Image Files – *.gif, *.jpg, *.jpeg, *.png
  4. TAR Files – *.tar
  5. TAR Files with gzip – *.tar.gz
  6. Zip Files – *.zip
  7. Gzip and Gzip2 Files – *.gz and *.bz2
  8. ISO Files
  9. Debian Files – *.deb
  10. RPM Files – *.rpm

Set the LESSOPEN environment variable to lesspipe

First, make sure the following is set in the environment variable.
$ set | grep less
LESSOPEN='|/usr/bin/lesspipe.sh %s'

Please note that you can also do the following to setup the lesspipe.
$ eval "($lesspipe)"

$ cat ~/.bashrc
eval "($lesspipe)"
  • lesspipe, lessfile are the input preprocessor for less, which lets it to open all types of files.
  • lesspipe allows you to open while the process of conversion is going on using pipe.
  • lessfile completes the conversion first, and then displays the content. This writes the converted thing to a temporary file then displays it.
  • You can also write your own input preprocessor, and use it.

File Type 1: How to open a pdf file?

It shows all the text in the pdf file clearly, but ignores the images. The output may have some special characters here and there. But it is definitely readable.
$ less Linux-101-Hacks.pdf
^LLinux 101 Hacks
www.thegeekstuff.com
o
o
o
Chapter 1: Powerful CD Command Hacks
cd is one of the most frequently used commands during a UNIX session.
The cd command hacks mentioned in this chapter will boost your productivity

File Type 2: How to open a word document file?

$ less pdb.doc
The Python Debugger Pdb
=======================

To use the debugger in its simplest form:

        >>> import pdb
        >>> pdb.run

The debugger's prompt is Pdb.  This will stop in the first
function call in

File Type 3: How to open a jpg, jpeg, png file?

While opening a image file (jpeg, jpg and png), less command shows the following information:
  • Name of the file
  • Type of file
  • Number of pixels — width & height
  • Size of the file
$ less testfile.jpeg
testfile.jpeg JPEG 2304x1728 2304x1728+0+0 DirectClass 8-bit 1.57222mb 0.550u 0:02
Note: Similar kind of information will be displayed for other image file types.

File Type 4: How to open an archived file (i.e *.tar) ?

While opening archive file it shows “ls -l” of the files available in the archive, so you can see the size of file, permissions of it and owner, group too.
$ less autocorrect.tar
-rwxrwxrwx anthony/anthony 84149 2009-02-02 03:20 autocorrect.dat
-rwxrwxrwx anthony/anthony 443 2009-02-02 03:21 generator.rb
-rwxrwxrwx anthony/anthony 181712 2009-02-02 03:21 autocorrect.vim

File Type 5: How to open an archived, compressed file in gzip format (i.e *.tar.gz format) ?

For the archived and compressed file also less command shows the output in “ls -l” format.
$ less XML-Parser-2.36.tar.gz
drwxr-xr-x matt/matt 0 2007-11-20 19:58 XML-Parser-2.36/
-rw-r--r-- matt/matt 25252 2007-11-20 19:52 XML-Parser-2.36/Changes
drwxr-xr-x matt/matt 0 2007-11-20 19:58 XML-Parser-2.36/Expat/
-rw-r--r-- matt/matt 3184 2003-07-27 16:37 XML-Parser-2.36/Expat/encoding.h
-rw-r--r-- matt/matt 33917 2007-11-20 19:54 XML-Parser-2.36/Expat/Expat.pm
-rw-r--r-- matt/matt 45555 2007-11-17 01:54 XML-Parser-2.36/Expat/Expat.xs

File Type 6: How to open an archived and compressed file in zip format (i.e *.zip format)?

It shows the details of archived and compressed file in the following format.
Archive: Archive name
Length Method Size Ratio Date Time CRC-32 Name
-------- ------ ------- ----- ---- ---- ------ ----

$ less bash-support.zip
Archive: bash-support.zip
Length Method Size Ratio Date Time CRC-32 Name
-------- ------ ------- ----- ---- ---- ------ ----
0 Stored 0 0% 01-30-09 19:56 00000000 ftplugin/
13488 Defl:N 2167 84% 01-30-09 19:53 b1bc6f3c ftplugin/sh.vim
5567 Defl:N 1880 66% 01-30-09 02:16 0017a875 README.bashsupport
0 Stored 0 0% 01-30-09 19:56 00000000 doc/
41013 Defl:N 11574 72% 01-30-09 19:50 0cc22a14 doc/bashsupport.txt
0 Stored 0 0% 01-30-09 19:56 00000000 bash-support/
0 Stored 0 0% 01-30-09 19:56 00000000 bash-support/templates/
513 Defl:N 187 64% 11-16-07 23:06 580ee37c bash-support/templates/bash-file-header
246 Defl:N 80 68% 01-31-07 21:51 54706588 bash-support/templates/bash-function-description
175 Defl:N 23 87% 01-31-07 21:51 22db9b2d bash-support/templates/bash-frame
0 Stored 0 0% 01-30-09 19:56 00000000 bash-support/rc/
6545 Defl:N 1807 72% 06-17-07 14:01 e7a27099 bash-support/rc/customization.vimrc
2144 Defl:N 526 76% 01-31-07 21:51 f3a5e8dd bash-support/rc/customization.gvimrc

File Type 7: How to open a compressed file gzip & bzip2.

Shows the content of the compressed file. If the file is only compressed and not archived then it shows the content of the file. However it does not shows the content of a zip file format, it shows the only the information in the format explained in File Type 7.

File Type 8: How to open an ISO file?

While opening an iso file, it shows information about the iso file and then shows the content of the file.
$ less knoppix_5.1.1.iso

CD-ROM is in ISO 9660 format
System id: LINUX
Volume id: KNOPPIX
Volume set id:
Publisher id: KNOPPER.NET
Data preparer id: www.knopper.net
Application id: KNOPPIX LIVE LINUX CD
Copyright File id:
Abstract File id:
Bibliographic File id:
Volume set size is: 1
Volume set sequence number is: 1
Logical block size is: 2048
Volume size is: 356532
El Torito VD version 1 found, boot catalog is in sector 763
Joliet with UCS level 3 found
Rock Ridge signatures version 1 found
Eltorito validation header:
Hid 1
Arch 0 (x86)
ID 'KNOPPER.NET'
Key 55 AA
Eltorito defaultboot header:
Bootid 88 (bootable)
Boot media 0 (No Emulation Boot)
Load segment 0
Sys type 0
Nsect 4
Bootoff 312 786

/KNOPPIX
/autorun.bat
/autorun.inf
/autorun.pif
/boot
/cdrom.ico
/index.html
/KNOPPIX/KNOPPIX
/KNOPPIX/KNOPPIX-FAQ-EN.txt

File Type 9: How to open a deb file?

When you open a Debian file, it shows the information about that package and also the “ls -l” of the files available in that package as shown below.
$ less lshw_02.08.01-1_i386.deb

lshw_02.08.01-1_i386.deb:
new debian package, version 2.0.
size 295134 bytes: control archive= 730 bytes.
678 bytes, 16 lines control
246 bytes, 4 lines md5sums
Package: lshw
Version: 02.08.01-1
Section: utils
Priority: optional
Architecture: i386
Depends: libc6 (>= 2.3.6-6), libgcc1 (>= 1:4.1.0), libstdc++6 (>= 4.1.0), lshw-common
Installed-Size: 716
Maintainer: Ghe Rivero
Description: information about hardware configuration
A small tool to provide detailed information on the hardware
configuration of the machine. It can report exact memory
configuration, firmware version, mainboard configuration, CPU version
and speed, cache configuration, bus speed, etc. on DMI-capable x86
systems, on some PowerPC machines (PowerMac G4 is known to work) and AMD64.
.
Information can be output in plain text, HTML or XML.

*** Contents:
drwxr-xr-x root/root 0 2006-08-10 04:15 ./
drwxr-xr-x root/root 0 2006-08-10 04:15 ./usr/
drwxr-xr-x root/root 0 2006-08-10 04:15 ./usr/bin/
-rwxr-xr-x root/root 665052 2006-08-10 04:15 ./usr/bin/lshw
drwxr-xr-x root/root 0 2006-08-10 04:15 ./usr/share/
drwxr-xr-x root/root 0 2006-08-10 04:15 ./usr/share/man/
drwxr-xr-x root/root 0 2006-08-10 04:15 ./usr/share/man/man1/
-rw-r--r-- root/root 1874 2006-08-10 04:15 ./usr/share/man/man1/lshw.1.gz
drwxr-xr-x root/root 0 2006-08-10 04:15 ./usr/share/lshw/
drwxr-xr-x root/root 0 2006-08-10 04:15 ./usr/share/doc/
drwxr-xr-x root/root 0 2006-08-10 04:15 ./usr/share/doc/lshw/
-rw-r--r-- root/root 999 2006-08-10 04:13 ./usr/share/doc/lshw/copyright
-rw-r--r-- root/root 1386 2006-08-10 04:13 ./usr/share/doc/lshw/changelog.Debian.gz

File Type 10: How to open a rpm file?

less command can show the details of the rpm package, and its contents.
$ less openssl-devel-0.9.7a-43.16.i386.rpm

openssl-devel-0.9.7a-43.16.i386.rpm:
Name : openssl-devel Relocations: (not relocatable)
Version : 0.9.7a Vendor: Scientific Linux , http://www.scientificlinux.org
Release : 43.16 Build Date: Thu May 3 12:18:00 2007
Install Date: (not installed) Build Host: lxcert-i386.cern.ch
Group : Development/Libraries Source RPM: openssl-0.9.7a-43.16.src.rpm
Size : 3845246 License: BSDish
Signature : DSA/SHA1, Wed May 9 15:03:20 2007, Key ID 5e03fde51d1e034b
Packager : Jaroslaw Polok
URL : http://www.openssl.org/
Summary : Files for development of applications which will use OpenSSL.
Description :
OpenSSL is a toolkit for supporting cryptography. The openssl-devel
package contains static libraries and include files needed to develop
applications which support various cryptographic algorithms and
protocols.

*** Contents:
/usr/include/openssl
/usr/include/openssl/aes.h
/usr/include/openssl/asn1.h
/usr/include/openssl/asn1_mac.h
/usr/include/openssl/asn1t.h
/usr/include/openssl/bio.h
/usr/include/openssl/blowfish.h
/usr/include/openssl/bn.h
/usr/include/openssl/buffer.h
/usr/include/openssl/cast.h
/usr/include/openssl/comp.h
/usr/include/openssl/conf.h
/usr/include/openssl/conf_api.h

Unix Less Command : 10 Tips for Effective Navigation

Posted by Admin / Labels: / Comments: (0)
I personally prefer to use less command to view files (instead of opening the file to view in an editor). Less is similar to more command, but less allows both forward and backward movements.

Moreover, less don’t require to load the whole file before viewing. Try opening a large log file in Vim editor and less — you’ll see the speed difference.
The navigation keys in less command are similar to Vim editor. In this article, let us look at few less command navigation and other operations which will make you a better command line warrior.

1. Less Command – Search Navigation

Once you’ve opened a log file (or any file) using less file-name, use the following keys to search. Please note that the match will be highlighted automatically by default.

Forward Search

  • / – search for a pattern which will take you to the next occurrence.
  • n – for next match in forward
  • N – for previous match in backward

Backward Search

  • ? – search for a pattern which will take you to the previous occurrence.
  • n – for next match in backward direction
  • N – for previous match in forward direction
Tip: If you dont bother about which direction the search is happening, and you want to search file path, or URL, such as “/home/ramesh/”, you can use backward search (?pattern) which will be handy as you don’t want to escape slashes each time.
Search Path
In forward: /\/home\/ramesh\/
In backward: ?/home/ramesh/

2. Less Command – Screen Navigation

Use the following screen navigation commands while viewing large log files.
  • CTRL+F – forward one window
  • CTRL+B – backward one window
  • CTRL+D – forward half window
  • CTRL+U – backward half window

3. Less Command – Line navigation

In a smaller chunk of data, where you want to locate particular error, you may want to navigate line by line using these keys:
  • j – navigate forward by one line
  • k – navigate backward by one line

4. Less Command – Other Navigations

The following are other navigation operations that you can use inside the less pager. .
  • G – go to the end of file
  • g – go to the start of file
  • q or ZZ – exit the less pager

5. Simulate tail -f inside less pager – Press F

Once you’ve opened a file using less command, any content that is appended to the file after that will not be displayed automatically. However, you can press F less command will show the status ‘waiting for data‘. This is as similar to ‘tail -f’.
Also, refer to our earlier article about how to view multiple logs files using tail -f.

6. Less Command – Count magic

Similar to Vim editor navigation command, you can give 10j to scroll 10 lines down, or 10k to go up by 10 lines.
  • 10j – 10 lines forward.
  • 10k – 10 lines backward.
  • CTRL+G – show the current file name along with line, byte and percentage statistics.

7. Other useful Less Command Operations

  • v – using the configured editor edit the current file.
  • h – summary of less commands
  • &pattern – display only the matching lines, not all.

8. Open any types of files using less command

As we discussed in our earlier article, you can use less command to Open & view 10 different file types.

9. Less Command – Marked navigation

When you are viewing a large log file using less command, you can mark a particular position and return back to that place again by using that mark.
  • ma – mark the current position with the letter ‘a’,
  • ‘a – go to the marked position ‘a’.

10. Less Command – Multiple file paging

Method 1: You can open multiple files by passing the file names as arguments.
$ less file1 file2
Method 2: While you are viewing file1, use :e to open the file2 as shown below.
$ less file1
:e file2
Navigation across files: When you opened more than two files ( for e.g – less * ), use the following keys to navigate between files.
  • :n – go to the next file.
  • :p – go to the previous file.