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Top Forums Shell Programming and Scripting How to delete all lines with less then 32 characters from a textfile? Post 302398717 by alister on Thursday 25th of February 2010 11:04:56 AM
Old 02-25-2010
What if Clint Eastwood was a UNIX sysadmin?

Quote:
Originally Posted by Harry Callahan
I know what you're thinking. "Does the unlink(2) syscall reclaim all resources associated with a file even if a process has the file open?" Well, to tell you the truth, in all this excitement I kind of lost track myself. But being as this is a .44 rm, the most powerful unix userland executable in the world, and would blow your file clean off, you've got to ask yourself one question: Do I feel lucky? Well, do ya, punk?
Code:
(rm data; sed '/.\{32\}/!d' > data) < data

To be clear, even if this works fine for you, it is a dangerous way of doing business. A power failure at just the right moment could leave you with no directory link to your data.

A safe, non-Dirty Harry approved version:
Code:
mv data data.bak; sed '/.\{32\}/!d' < data.bak > data


Last edited by alister; 02-25-2010 at 12:15 PM..
 

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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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