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Full Discussion: variable substitution in sed
Top Forums Shell Programming and Scripting variable substitution in sed Post 302409407 by sugan on Thursday 1st of April 2010 04:20:47 AM
Old 04-01-2010
variable substitution in sed

Hi,
I have to insert a line at a particular line number in my file. But the line number is not fixed and it will vary every time. So, I have to use a variable to get the line number

I know we can use sed to insert lines at a particular line number but it does not work with variable substitution.

Ex:
Code:
sed '1i\
xxxx' file

The above code works. But the below one does not work.
Code:
n=2
sed '$n i\
xxxx' file

How to handle this variable substitution using sed. I am also ok with any solution without using sed.

Thanks,
Sugan

Last edited by pludi; 04-01-2010 at 05:40 AM.. Reason: code tags, please...
 

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curs_deleteln(3X)														 curs_deleteln(3X)

NAME
deleteln, wdeleteln, insdelln, winsdelln, insertln, winsertln - delete and insert lines in a curses window SYNOPSIS
#include <curses.h> int deleteln(void); int wdeleteln(WINDOW *win); int insdelln(int n); int winsdelln(WINDOW *win, int n); int insertln(void); int winsertln(WINDOW *win); DESCRIPTION
The deleteln and wdeleteln routines delete the line under the cursor in the window; all lines below the current line are moved up one line. The bottom line of the window is cleared. The cursor position does not change. The insdelln and winsdelln routines, for positive n, insert n lines into the specified window above the current line. The n bottom lines are lost. For negative n, delete n lines (starting with the one under the cursor), and move the remaining lines up. The bottom n lines are cleared. The current cursor position remains the same. The insertln and winsertln routines, insert a blank line above the current line and the bottom line is lost. RETURN VALUE
All routines return the integer ERR upon failure and an OK (SVr4 specifies only "an integer value other than ERR") upon successful comple- tion. PORTABILITY
These functions are described in the XSI Curses standard, Issue 4. The standard specifies that they return ERR on failure, but specifies no error conditions. NOTES
Note that all but winsdelln may be macros. These routines do not require a hardware line delete or insert feature in the terminal. In fact, they won't use hardware line delete/insert unless idlok(..., TRUE) has been set on the current window. SEE ALSO
curses(3X) curs_deleteln(3X)
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