Sponsored Content
Top Forums Shell Programming and Scripting Emulate group-by in shell script Post 302994549 by durden_tyler on Friday 24th of March 2017 11:04:09 AM
Old 03-24-2017
Thanks a lot for your comments, Scrutinizer. Those are all very valid points.

While writing the script, the biggest source of my consternation was the repetition of this construct
Code:
${line##*,}

in lines 19 and 21.
I would've loved to do this:
1) Extract the 2nd token from the line and assign it to a temp variable and check if $temp is greater than $min.
2) If comparison test is true, i.e. $temp is greater than $min, then assign the $temp to max.

Some languages like C, Perl and (I think) Python allow this.
Kind of like this idiom in K&R, which accomplishes three things: fetch, assignment and comparison.

Code:
 while ((c = getchar()) != EOF) {

Your suggestion of using IFS along with the read function:

Quote:
Originally Posted by Scrutinizer
...An alternative would be to do the splitting of values while reading the line
Code:
while IFS=, read operation value

then the variable expansions would not need to be used..
is a clean way of avoiding that repetition.
 

10 More Discussions You Might Find Interesting

1. Shell Programming and Scripting

Script to emulate ls -lh?

Does anyone have a script they would like to share that emulates "ls -lh" in ksh on Solaris 8? Yeah, I know. Real men don't need that wimpy "h." Well, I'm a wimp. ;) (0 Replies)
Discussion started by: shew01
0 Replies

2. Shell Programming and Scripting

Shell quiz: emulate an associative array

Most shells flavors do not have associative arrays a.k.a. maps. How would you emulate an associative array? I had this problem once and found a working solution, but I don't want to spoil the game hence I wont tell it. Wonder if anyone comes up with something better. (5 Replies)
Discussion started by: colemar
5 Replies

3. Shell Programming and Scripting

HELP! Group by in shell script (awk/sed?)

Hello, Could some expert soul please help me with this? I have following file format - task time abc 5 xyz 4 abc 5 xyz 3 ddd 10 ddd 2 I need to generate output as - task ... (5 Replies)
Discussion started by: sncoupons
5 Replies

4. Shell Programming and Scripting

How to emulate ^S/^Q from a script

Hi, I wrote a little menu script that searches through another script you specify and displays step-names and next to it the text of the step. The scripts are converted JCL from mainframe. It alows you to select steps you want and will then create a new script which includes only the steps you... (5 Replies)
Discussion started by: AliceD
5 Replies

5. Shell Programming and Scripting

Shell script to rename a group of files

Hello, I am having 1800 files in a directory with a specified format, like amms_850o_prod.000003uNy amms_850o_prod.000003u8x amms_850o_prod.000003taP amms_850o_prod.000003tKy amms_850o_prod.000003si4 amms_850o_prod.000003sTP amms_850o_prod.000003sBg amms_850o_prod.000003rvx... (12 Replies)
Discussion started by: atlantis
12 Replies

6. Shell Programming and Scripting

"group by" using shell script?

not sure if it's called "group by" , but what i'm going to do is like this: i have a file below: 192.168.1.10 192.168.1.10 192.168.1.10 192.168.1.11 192.168.1.15 192.168.1.15 192.168.1.20 192.168.1.22 then i hope to get the result like this: 192.168.1.10 : 3 192.168.1.11 : 1... (6 Replies)
Discussion started by: tiger2000
6 Replies

7. Shell Programming and Scripting

Shell Script to ignore # and take corresponding user and group

Hi, I have a following file: role.IMPACT_USER.user=admin role.IMPACT_USER.user=dd12345 role.IMPACT_USER.user=ss76767 #role.IMPACT_USER.user=root #role.IMPACT_USER.group=System role.IMPACT_USER.group=ImpactUser #Description: Allow users to login in to Impact, start and stop service... (5 Replies)
Discussion started by: dbashyam
5 Replies

8. Shell Programming and Scripting

Emulate fgrep -f in perl

Is there any equivalent of the below requirement in perl fgrep -f file1 file2 > file3 (2 Replies)
Discussion started by: aravindj80
2 Replies

9. Shell Programming and Scripting

Shell script - group by

Hi, I have text file as shown below. root 25 oracle 25 batch 30 griduser 32 admin 35 root 25 oracle 25 batch 30 griduser 32 oracle 25 batch 30 griduser 32 xuser 45 admin 35 I want to group by based on user name, and the output need to be as below. Not necessary the username to be... (10 Replies)
Discussion started by: baladelaware73
10 Replies

10. Shell Programming and Scripting

Shell Script to Group by Based on Multiple Fields in a file

Hi, I want to know if there is any simple approach to SUM a field based on group by of different fields for e.g. file1.txt contains below data 20160622|XXX1||50.00||50.00|MONEY|Plan1| 20160622|XXX1||100.00||100.00|MONEY|Plan1| 20160623|XXX1||25.00||25.00|MONEY|Plan1|... (3 Replies)
Discussion started by: cnu_theprince
3 Replies
ustrtok(3alleg4)						  Allegro manual						  ustrtok(3alleg4)

NAME
ustrtok - Retrieves tokens from a string. Allegro game programming library. SYNOPSIS
#include <allegro.h> char *ustrtok(char *s, const char *set); DESCRIPTION
This function retrieves tokens from `s' which are delimited by characters from `set'. To initiate the search, pass the string to be searched as `s'. For the remaining tokens, pass NULL instead. Warning: Since ustrtok alters the string it is parsing, you should always copy the string to a temporary buffer before parsing it. Also, this function is not re-entrant (ie. you cannot parse two strings at the same time). Example: char *word; char string[]="some-words with dashes"; char *temp = ustrdup(string); word = ustrtok(temp, " -"); while (word) { allegro_message("Found `%s' ", word); word = ustrtok(NULL, " -"); } free(temp); RETURN VALUE
Returns a pointer to the token, or NULL if no more are found. SEE ALSO
uconvert(3alleg4), ustrchr(3alleg4), ustrrchr(3alleg4), ustrstr(3alleg4), ustrpbrk(3alleg4), ustrtok_r(3alleg4), allegro_message(3alleg4), ustrncpy(3alleg4), exgui(3alleg4) Allegro version 4.4.2 ustrtok(3alleg4)
All times are GMT -4. The time now is 04:54 AM.
Unix & Linux Forums Content Copyright 1993-2022. All Rights Reserved.
Privacy Policy