Sponsored Content
Top Forums Shell Programming and Scripting replacing field in specific line in a file Post 302447938 by Corona688 on Tuesday 24th of August 2010 06:26:08 PM
Old 08-24-2010
The problem is that file I/O has no "insert" operation: If the new data is a different length than the old you need to rewrite everything after the change.

There's way better, faster, and simpler ways than the 'cut' utility to read fields from a data file, but it's difficult to help without seeing the rest of your program. It'd also tell me what other fields from that line you have, since just knowing the balance isn't enough to find and edit that exact line...
This User Gave Thanks to Corona688 For This Post:
 

10 More Discussions You Might Find Interesting

1. Shell Programming and Scripting

Replacing the last field of a line.

Hi, I wrote a script which extracts data from 2 tables (joining the tables together) and outputs the fields to a csv file. the output may look something like scenario 1: a,b,c,d,1,2,3,4 or scenario 2: a,b,c,d,,,, now, in the second scenario, there are some empty fields at the end of... (3 Replies)
Discussion started by: Darek
3 Replies

2. UNIX for Dummies Questions & Answers

replacing string in a column on a specific line

hi, i currently have a file with columns similar to this customer name owed CID123 John 300 CID342 harry 500 at present i use use awk to find the amount owed by the customer using the customer ID (CID). if the customer spends more money how would i go about using sed/awk etc to... (2 Replies)
Discussion started by: skinnygav
2 Replies

3. Shell Programming and Scripting

How to append a character to the last but one field on a specific line?

Hi Guys, I have a file like this: aaa b c d e f fsss g h i k l qqq r t h n I want: aaa b c d e f fsss g h i k l qqq r t h , n ggg p t e d u qqq i o s , k (2 Replies)
Discussion started by: npatwardhan
2 Replies

4. Shell Programming and Scripting

SED Replacing all but one regex match on a line or specific matches

Hi, I'm attempting to rename some files that have spaces in them. Without linking sed commands together is it possible to replace the first three "." to " ". File.name.is.long.ext -> File name is long.ext I can get the desired effect with echo "File.name.is.long.ext" | sed 's/\./ /g;s/... (5 Replies)
Discussion started by: vectox
5 Replies

5. Shell Programming and Scripting

Using awk to read a specific line and a specific field on that line.

Say the input was as follows: Brat 20 x 1000 32rf Pour 15 p 1621 05pr Dart 10 z 1111 22xx My program prompts for an input, what I want is to use the input to locate a specific field. Like if I type in, "Pou" then it would return "Pour" and just "Pour" I currently have this line but it is... (6 Replies)
Discussion started by: Bungkai
6 Replies

6. Shell Programming and Scripting

Replace specific field on specific line sed or awk

I'm trying to update a text file via sed/awk, after a lot of searching I still can't find a code snippet that I can get to work. Brief overview: I have user input a line to a variable, I then find a specific value in this line 10th field in this case. After asking for new input and doing some... (14 Replies)
Discussion started by: crownedzero
14 Replies

7. Shell Programming and Scripting

Update specific field in a line of text file

I have a text file like this: subject1:LecturerA:10 subject2:LecturerA:40 if I was given string in column 1 and 2 (which are subject 1 and LecturerA) , i need to update 3rd field of that line containing that given string , which is, number 10 need to be updated to 100 ,for example. The... (6 Replies)
Discussion started by: bmtoan
6 Replies

8. Shell Programming and Scripting

Replacing nth field with nth_text for each line in a file

Hi All, I am very new to shell scripting and tried to search this in the forum but no luck. Requirment: I have an input file which is comma separated. I need to replace the value in 4th column with another value. This has to happen for all the lines in the file. Sample data: Input... (2 Replies)
Discussion started by: arunkumarsd
2 Replies

9. Shell Programming and Scripting

Replacing entire fields with specific text at end or beginning of field

Greetings. I've got a csv file with data along these lines: Spumoni's Pizza Place, Placemats n Things, Just Lamps Counterfeit Dollars by Vinnie, Just Shades, Dollar StoreI want to replace the entire comma-delimited field if it matches something ending in "Place" or beginning with "Dollar",... (2 Replies)
Discussion started by: palmfrond
2 Replies

10. UNIX for Beginners Questions & Answers

How do you preserve the max length of a line after replacing a specific value?

I'm new with scripting and I can't seem to figure out what I should do to get the output that I want. My file content would be below. ID2|ID3 |ID4|ID5 | I'm trying to replace the field of ID3 which has a fixed length of 10 characters, for each entry I have placed on a .txt file... (5 Replies)
Discussion started by: asdfghjkl
5 Replies
cut(1)							      General Commands Manual							    cut(1)

Name
       cut - cut out selected fields of each line of a file

Syntax
       cut -clist [file1 file2...]
       cut -flist [-dchar] [-s] [file1 file2...]

Description
       Use  the  command to cut out columns from a table or fields from each line of a file.  The fields as specified by list can be fixed length,
       that is, character positions as on a punched card (-c option), or the length can vary from line to line and be marked with a  field  delim-
       iter character like tab (-f option).  The command can be used as a filter.  If no files are given, the standard input is used.

       Use to make horizontal ``cuts'' (by context) through a file, or to put files together in columns.  To reorder columns in a table, use and

Options
       list	   Specifies  ranges  that must be a comma-separated list of integer field numbers in increasing order.  With optional - indicates
		   ranges as in the -o option of nroff/troff for page ranges; for example, 1,4,7; 1-3,8; -5,10 (short for 1-5,10);  or	3-  (short
		   for third through last field).

       -clist	   Specifies character positions to be cut out.  For example, -c1-72 would pass the first 72 characters of each line.

       -flist	   Specifies  the  fields  to be cut out.  For example, -f1,7 copies the first and seventh field only.	Lines with no field delim-
		   iters are passed through intact (useful for table subheadings), unless -s is specified.

       -dchar	   Uses the specified character as the field delimiter.  Default is tab.  Space or other characters with special  meaning  to  the
		   shell must be quoted.  The -d option is used only in combination with the -f option, according to XPG3 and SVID2/SVID3.

       -s	   Suppresses  lines  with  no	delimiter  characters.	 Unless  specified, lines with no delimiters are passed through untouched.
		   Either the -c or -f option must be specified.

Examples
       Mapping of user IDs to names:
       cut -d: -f1,5 /etc/passwd
       To set name to the current login name for the csh shell:
       set name=`who am i | cut -f1 -d" "`
       To set name to the current login name for the sh, sh5, and ksh shells:
       name=`who am i | cut -f1 -d" "`

Diagnostics
       "line too long"	   A line can have no more than 511 characters or fields.

       "bad list for c/f option"
			   Missing -c or -f option or incorrectly specified list.  No error occurs if a line has fewer fields than the list  calls
			   for.

       "no fields"	   The list is empty.

See Also
       grep(1), paste(1)

																	    cut(1)
All times are GMT -4. The time now is 10:15 PM.
Unix & Linux Forums Content Copyright 1993-2022. All Rights Reserved.
Privacy Policy