Linux/ FreeBSD GNU GCC Common option for C compiler

Posted on in Categories Linux, UNIX last updated November 29, 2007

gcc is a GNU project C and C++ compiler for Linux, UNIX, FreeBSD etc. From the wikipedia:

GCC is a key component of the GNU toolchain. As well as being the official compiler of the GNU system, GCC has been adopted as the standard compiler by most other modern Unix-like computer operating systems, including Linux, the BSD family and Mac OS X. GCC has been ported to a wide variety of computer architectures, and is widely deployed as a tool in commercial and closed development environments.

Common gcc options:

cc -E :preprocessor
cc -S :create or show assembly coding
cc -o :object filename
cc -g :debug info
cc -O :optimized code
cc -O2 :optimized code with optimization level increased
cc -Wall :create or show all warning
cc -D_SYMBOL_ : Symbol for prerpcessor

You can use gcc instead of cc.

How to: Extract files from ISO CD images in Linux

Posted on in Categories Debian Linux, File system, Gentoo Linux, Howto, Linux, RedHat/Fedora Linux, Suse Linux, Sys admin, Tips, Ubuntu Linux last updated November 29, 2007

Under many situations you may need to get a single file/many files from Linux ISO image.

You can mount ISO images via the loop device. You need to use mount command. First login as a root user:

Extract File(s) Under Linux OS

Let us assume that your ISO image name is disk1.iso.

Step # 1: First you need to create a directory /mnt/iso

# mkdir /mnt/iso
# mount -o loop disk1.iso /mnt/iso

Step # 3: Extract file

Now you can easily copy file called file.txt from iso disk image to /tmp directory :

# cd /mnt/iso
# cp file.txt /tmp

Step # 4: Copy foo.rpm from ISO disk image:

# cd /mnt/iso/RedHat/RPMS
# cp foo.rpm /tmp 

Extract File(s) Under Windows XP or Vista Os

Windows do not have in built capability as provided by Linux to extract file. Luckly many third party software exist my favorite is Winimage Download trial version (I’m sure you will love to registered this tiny utility later):

1) Install Winimage software

2) Just double click on Linux ISO file

3) Select the desired file and hit CTRL + X (or from Image menu select extract)

For more information read man pages:

man cp
man mv
man rpm
man mount
man mkdir

Linux Password Trick With Immutable Bit Using chattr Command

Posted on in Categories Linux, RedHat/Fedora Linux, Security last updated January 26, 2015

[icon type=”linux”]You can make a file immutable on Linux with the help of utility called chattr. One can changes the file attributes on a Linux second extended file system. The operator + causes the selected attributes to be added to the existing attributes of the files; - causes them to be removed; and = causes them to be the only attributes that the files have.

How to mount remote windows partition (windows share) under Linux

Posted on in Categories CentOS, File system, Howto, Linux, RedHat/Fedora Linux, Suse Linux, Sys admin, Tip of the day, Ubuntu Linux, UNIX, Windows, Windows server last updated August 3, 2007

All files accessible in a Linux (and UNIX) system are arranged in one big tree, the file hierarchy, rooted at /. These files can be spread out over several devices. The mount command serves to attach the file system found on some device to the big file tree.

Use the mount command to mount remote windows partition or windows share under Linux as follows:

Procedure to mount remote windows partition (NAS share)

1) Make sure you have following information:
==> Windows username and password to access share name
==> Sharename (such as //server/share) or IP address
==> root level access on Linux

2) Login to Linux as a root user (or use su command)

3) Create the required mount point:
# mkdir -p /mnt/ntserver
4) Use the mount command as follows:
# mount -t cifs //ntserver/download -o username=vivek,password=myPassword /mnt/ntserver

Use following command if you are using Old version such as RHEL <=4 or Debian <= 3: # mount -t smbfs -o username=vivek,password=D1W4x9sw //ntserver/download /mnt/ntserver

5) Access Windows 2003/2000/NT share using cd and ls command:
# cd /mnt/ntserver; ls -l

  • -t smbfs : File system type to be mount (outdated, use cifs)
  • -t cifs : File system type to be mount
  • -o : are options passed to mount command, in this example I had passed two options. First argument is password (vivek) and second argument is password to connect remote windows box
  • //ntserver/download : Windows 2000/NT share name
  • /mnt/ntserver Linux mount point (to access share after mounting)

See also:

Updated for accuracy on Aug-8-2007, 8:19PM.