Tag Archives: bsd

[sed] Replace a tab character using sed

07 Monday May 2012

Posted by in sed

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Here’s how to replace all instances of TAB in a file input_file by, say comma (,), using sed

$ sed 's/<TAB>/,/g' input_file

But what is <TAB> above? On Linux systems you may just type \t (which is the regular expression for TAB) in place of <TAB>. However,  on some other systems (e.g., OSX with FreeBSD) it does not work. In cases where it doesn’t work, invoke <TAB> by hitting Control+v followed by the TAB key. This may alternatively be achieved by hitting Control+v followd by Control+i, as well.

References: ATOzTOA, Stack Overflow.

[unix] Change default login shell

26 Monday Oct 2009

Posted by in unix

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I just stumbled upon a few ways to change the default login shell to bash:

The easiest one is

$ chsh -s /bin/bash username

On some machines you may have to use ypcsh instead of chsh. The full path of the shell executable must be specified.

But if you have root access you may have the option to use either of the following two as well:

  • $ usermod -s bash username
  • Change it by editing the entry for the user in /etc/passwd file, manually.

If none of the above works, here’s a workaround!

N.B. Make sure that the desired shell is listed in /etc/shells file.

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