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Top Forums Shell Programming and Scripting writing in a file's particular column number of every line during runtime Post 302552469 by Corona688 on Saturday 3rd of September 2011 06:19:39 PM
Old 09-03-2011
Quote:
Originally Posted by arindamlive
i have this following file named test.txt whose content is

Hello
World

Whats Up?


and i execute the following command
x="Hey"
awk -v LINE=3 -v COL=1 -v VAL="x" '{ if(NR == LINE) $COL=VAL } 1' test.txt /tmp/$$
That's not precisely what I suggested. You left out some characters as well as leaving out two important steps.

You never said x was a variable, either. I'll have to change it for that.

Code:
awk -v LINE=3 -v COL=1 -v VAL="$x" '{ if(NR == LINE) $COL=VAL } 1' test.txt > /tmp/$$
cat /tmp/$$ > test.txt
rm test.txt

Really though -- is editing-in-place such a good idea? At least test your data somehow before overwriting it.
This User Gave Thanks to Corona688 For This Post:
 

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WCWIDTH(3)						   BSD Library Functions Manual 						WCWIDTH(3)

NAME
wcwidth -- number of column positions of a wide-character code LIBRARY
Standard C Library (libc, -lc) SYNOPSIS
#include <wchar.h> int wcwidth(wchar_t wc); DESCRIPTION
The wcwidth() function determines the number of column positions required to display the wide character wc. RETURN VALUES
The wcwidth() function returns 0 if the wc argument is a nul wide character (L''), -1 if wc is not printable, otherwise it returns the num- ber of column positions the character occupies. EXAMPLES
This code fragment reads text from standard input and breaks lines that are more than 20 column positions wide, similar to the fold(1) util- ity: wint_t ch; int column, w; column = 0; while ((ch = getwchar()) != WEOF) { w = wcwidth(ch); if (w > 0 && column + w >= 20) { putwchar(L' '); column = 0; } putwchar(ch); if (ch == L' ') column = 0; else if (w > 0) column += w; } SEE ALSO
iswprint(3), wcswidth(3) STANDARDS
The wcwidth() function conforms to IEEE Std 1003.1-2001 (``POSIX.1''). BSD
August 17, 2004 BSD
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