Sponsored Content
Top Forums UNIX for Beginners Questions & Answers Fetching 1st Column and Last n Columns Post 302983162 by rbatte1 on Friday 7th of October 2016 06:41:48 AM
Old 10-07-2016
Hello Don,

Quote:
Hi Robin,
The command:
Code:
columns=$(set - $(head -1 input_file | tr " " "_") ; echo $#)  # Count number of columns today.  The tr eliminates spaces, just for counting columns

can be changed to:
Code:
IFS= read -r line < input_file
columns=$(IFS=$tab; set -- $line; echo $#)

using just shell built-ins without needing to exec head and tr. Note also that the standards explicitly stated that:
Code:
set - arg...

produces unspecified results starting in the 2004 revision of the standard; that form was deprecated in the 1992 edition of the standard with the preferred form being:
Code:
set -- arg...

Many thanks for the comments (again) and I'm delighted to have a way to save a few processes. I imaging the cost of running what I had in a loop reading a large file and counting columns for each record would be quite expensive. This is very useful.

Regarding the standards change, I was unaware so this is really useful and will hopefully stop me failing in the future.


Kindest regards,
Robin
 

10 More Discussions You Might Find Interesting

1. Shell Programming and Scripting

How to check Null values in a file column by column if columns are Not NULLs

Hi All, I have a table with 10 columns. Some columns(2nd,4th,5th,7th,8th and 10th) are Not Null columns. I'll get a tab-delimited file and want to check col by col and generate seperate error code for each col eg:102 if 2nd col value is NULL and 104 if 4th col value is NULL so on... I am a... (7 Replies)
Discussion started by: Mandab
7 Replies

2. UNIX for Dummies Questions & Answers

two files.say a and b.both have long columns.i wanna match the column fron 1st file w

ex: a file has : 122323 123456456 125656879 678989965t635 234323432 b has : this is finance no. this is phone no this is extn ajkdgag idjsidj i want the o/p as: 122323 his is finance no. 123456456 this is phone no 123456456 ... (4 Replies)
Discussion started by: TRUPTI
4 Replies

3. Shell Programming and Scripting

Help In fetching the 2nd Peak value of a column

Hi, We have a requirement of calculating the AVG, Peak and 2nd Peak (Say Peak2) of a column in a text file. We are able to get Avg and Peak but we are finding difficulty in getting the 2nd Peak. I tried using the AWK but in vainL. Please find the below Script i have written for fetching AVG and... (3 Replies)
Discussion started by: mahesh Madpathi
3 Replies

4. Shell Programming and Scripting

Combine columns from many files but keep them aligned in columns-shorter left column issue

Hello everyone, I searched the forum looking for answers to this but I could not pinpoint exactly what I need as I keep having trouble. I have many files each having two columns and hundreds of rows. first column is a string (can have many words) and the second column is a number.The files are... (5 Replies)
Discussion started by: isildur1234
5 Replies

5. Shell Programming and Scripting

Fetching columns from .csv file except last column

Hi, i have below list of files so i just want the name of the files in one parameter and not the timestamp. i want only GIDW_Dy_Tm_Seg_Sls_legacy_PL_0_0_ in variable of all files. GIDW_Dy_Tm_Seg_Sls_legacy_PL_0_0_20131001101800.csv GIDW_Dly_Sls_legacy_RO_0_0_20131001172001.csv ... (9 Replies)
Discussion started by: renuk
9 Replies

6. Shell Programming and Scripting

Fetching values in CSV file based on column name

input.csv: Field1,Field2,Field3,Field4,Field4 abc ,123 ,xyz ,000 ,pqr mno ,123 ,dfr ,111 ,bbb output: Field2,Field4 123 ,000 123 ,111 how to fetch the values of Field4 where Field2='123' I don't want to fetch the values based on column position. Instead want to... (10 Replies)
Discussion started by: bharathbangalor
10 Replies

7. UNIX for Dummies Questions & Answers

Want the UNIX code - I want to sum of the 1st column wherever the first 2nd and 3rd columns r equal

I have the code for the below things.. File1 has the content as below 8859 0 subscriberCreate 18 0 subscriberPaymentMethodChange 1650 0 subscriberProfileUpdate 7668 0 subscriberStatusChange 13 4020100 subscriberProfileUpdate 1 4020129 subscriberStatusChange 2 4020307 subscriberCreate 8831... (5 Replies)
Discussion started by: Mahen
5 Replies

8. Linux

Print the 1st column and the value in 2nd or 3rd column if that is different from the values in 1st

I have file that looks like this, DIP-17571N|refseq:NP_651151 DIP-17460N|refseq:NP_511165|uniprotkb:P45890 DIP-17571N|refseq:NP_651151 DIP-19241N|refseq:NP_524261 DIP-19241N|refseq:NP_524261 DIP-17151N|refseq:NP_524316|uniprotkb:O16797 DIP-19588N|refseq:NP_731165 ... (2 Replies)
Discussion started by: Syeda Sumayya
2 Replies

9. Shell Programming and Scripting

awk to Sum columns when other column has duplicates and append one column value to another with Care

Hi Experts, Please bear with me, i need help I am learning AWk and stuck up in one issue. First point : I want to sum up column value for column 7, 9, 11,13 and column15 if rows in column 5 are duplicates.No action to be taken for rows where value in column 5 is unique. Second point : For... (1 Reply)
Discussion started by: as7951
1 Replies

10. UNIX for Beginners Questions & Answers

Compare 1st column from 2 file and if match print line from 1st file and append column 7 from 2nd

hi I have 2 file with more than 10 columns for both 1st file apple,0,0,0...... orange,1,2,3..... mango,2,4,5..... 2nd file apple,2,3,4,5,6,7... orange,2,3,4,5,6,8... watermerlon,2,3,4,5,6,abc... mango,5,6,7,4,6,def.... (1 Reply)
Discussion started by: tententen
1 Replies
RTBL(3) 						   BSD Library Functions Manual 						   RTBL(3)

NAME
rtbl_create, rtbl_destroy, rtbl_set_flags, rtbl_get_flags, rtbl_set_prefix, rtbl_set_separator, rtbl_set_column_prefix, rtbl_set_column_affix_by_id, rtbl_add_column, rtbl_add_column_by_id, rtbl_add_column_entry, rtbl_add_column_entry_by_id, rtbl_new_row, rtbl_format -- format data in simple tables LIBRARY
The roken library (libroken, -lroken) SYNOPSIS
#include <rtbl.h> int rtbl_add_column(rtbl_t table, const char *column_name, unsigned int flags); int rtbl_add_column_by_id(rtbl_t table, unsigned int column_id, const char *column_header, unsigned int flags); int rtbl_add_column_entry(rtbl_t table, const char *column_name, const char *cell_entry); int rtbl_add_column_entry_by_id(rtbl_t table, unsigned int column_id, const char *cell_entry); rtbl_t rtbl_create(void); void rtbl_destroy(rtbl_t table); int rtbl_new_row(rtbl_t table); int rtbl_set_column_affix_by_id(rtbl_t table, unsigned int column_id, const, char, *prefix", const char *suffix); int rtbl_set_column_prefix(rtbl_t table, const char *column_name, const char *prefix); unsigned int rtbl_get_flags(rtbl_t table); void rtbl_set_flags(rtbl_t table, unsigned int flags); int rtbl_set_prefix(rtbl_t table, const char *prefix); int rtbl_set_separator(rtbl_t table, const char *separator); int rtbl_format(rtbl_t table, FILE, *file"); DESCRIPTION
This set of functions assemble a simple table consisting of rows and columns, allowing it to be printed with certain options. Typical use would be output from tools such as ls(1) or netstat(1), where you have a fixed number of columns, but don't know the column widths before hand. A table is created with rtbl_create() and destroyed with rtbl_destroy(). Global flags on the table are set with rtbl_set_flags and retrieved with rtbl_get_flags. At present the only defined flag is RTBL_HEADER_STYLE_NONE which suppresses printing the header. Before adding data to the table, one or more columns need to be created. This would normally be done with rtbl_add_column_by_id(), column_id is any number of your choice (it's used only to identify columns), column_header is the header to print at the top of the column, and flags are flags specific to this column. Currently the only defined flag is RTBL_ALIGN_RIGHT, aligning column entries to the right. Columns are printed in the order they are added. There's also a way to add columns by column name with rtbl_add_column(), but this is less flexible (you need unique header names), and is considered deprecated. To add data to a column you use rtbl_add_column_entry_by_id(), where the column_id is the same as when the column was added (adding data to a non-existent column is undefined), and cell_entry is whatever string you wish to include in that cell. It should not include newlines. For columns added with rtbl_add_column() you must use rtbl_add_column_entry() instead. rtbl_new_row() fills all columns with blank entries until they all have the same number of rows. Each column can have a separate prefix and suffix, set with rtbl_set_column_affix_by_id; rtbl_set_column_prefix allows setting the prefix only by column name. In addition to this, columns may be separated by a string set with rtbl_set_separator (by default columns are not seprated by anything). The finished table is printed to file with rtbl_format. EXAMPLES
This program: #include <stdio.h> #include <rtbl.h> int main(int argc, char **argv) { rtbl_t table; table = rtbl_create(); rtbl_set_separator(table, " "); rtbl_add_column_by_id(table, 0, "Column A", 0); rtbl_add_column_by_id(table, 1, "Column B", RTBL_ALIGN_RIGHT); rtbl_add_column_by_id(table, 2, "Column C", 0); rtbl_add_column_entry_by_id(table, 0, "A-1"); rtbl_add_column_entry_by_id(table, 0, "A-2"); rtbl_add_column_entry_by_id(table, 0, "A-3"); rtbl_add_column_entry_by_id(table, 1, "B-1"); rtbl_add_column_entry_by_id(table, 2, "C-1"); rtbl_add_column_entry_by_id(table, 2, "C-2"); rtbl_add_column_entry_by_id(table, 1, "B-2"); rtbl_add_column_entry_by_id(table, 1, "B-3"); rtbl_add_column_entry_by_id(table, 2, "C-3"); rtbl_add_column_entry_by_id(table, 0, "A-4"); rtbl_new_row(table); rtbl_add_column_entry_by_id(table, 1, "B-4"); rtbl_new_row(table); rtbl_add_column_entry_by_id(table, 2, "C-4"); rtbl_new_row(table); rtbl_format(table, stdout); rtbl_destroy(table); return 0; } will output the following: Column A Column B Column C A-1 B-1 C-1 A-2 B-2 C-2 A-3 B-3 C-3 A-4 B-4 C-4 HEIMDAL
June 26, 2004 HEIMDAL
All times are GMT -4. The time now is 10:17 PM.
Unix & Linux Forums Content Copyright 1993-2022. All Rights Reserved.
Privacy Policy