Sponsored Content
Top Forums UNIX for Dummies Questions & Answers Faster than nested while read loops? Post 302545791 by jim mcnamara on Tuesday 9th of August 2011 01:52:28 PM
Old 08-09-2011
The fastest way, arguably, to read a file is process substitutuion in bash, ksh, or zsh.

Code:
a=$(< filename)
b=$(< filename2)

But based on his example and output it looks like he is pasting.
 

10 More Discussions You Might Find Interesting

1. Shell Programming and Scripting

Grepping within nested for loops

Good morning - I have publication lists from 34 different faculty members. I need to end up with the numbers of publications in common across all 34 faculty. I need to grep person1 (last name) in list2, person1 in list3, person1 in list 4, etc., then person2 in list3, person 2 in list4, etc.,... (2 Replies)
Discussion started by: Peggy White
2 Replies

2. Shell Programming and Scripting

nested for loops

I need help getting over this bump on how nested for loops work in shell. Say i was comparing files in a directory in any other language my for loop would look like so for(int i=0;to then end; i++) for(int y = i+1; to the end; y++) I can't seem to understand how i can translate that... (5 Replies)
Discussion started by: taiL
5 Replies

3. Shell Programming and Scripting

Nested while loops (ksh scripting)

You can use one while inside another? I made the following script (without really knowing if I can use two while) to get 3 numbers different from each other at random: num1=$(( $RANDOM % 10 )) num2=$num1 while do num2=$(( $RANDOM % 10 )) done num3=$num1 while do while do... (1 Reply)
Discussion started by: ale.dle
1 Replies

4. Shell Programming and Scripting

Need help with Regular Expressions and nested loops

Ok... am going slightly loopy trying to get this working (no pun intended) What I need is to modify this code which takes a string input then echo's each character on a seperate line, to do the same thing but to put DIGIT: in front of numbers and LETTER: in front of letters. I know a regular... (5 Replies)
Discussion started by: U_C_Dispatj
5 Replies

5. Shell Programming and Scripting

KSH nested loops?

KSH isn't my strong suit but it's what my company has to offer. I've got a script with two nested loops, a FOR and UNTIL, and that works fine. When I add a CASE into the mix I end up getting "Unexpected 'done' at line xx" errors. Any suggestions on this? for divi in at ce ci cm co de di fl... (9 Replies)
Discussion started by: mrice
9 Replies

6. Shell Programming and Scripting

Nested for loops

Greetings All, The following script attempts to enumerate all users in all groups in the group file(GROUP) and echo the following information: GROUP ---> USER The script is as follows: IFS="," for GROUP in `ypcat -k group | cut -d" " -f1` do for USER in `ypcat -k group... (13 Replies)
Discussion started by: jacksolm
13 Replies

7. UNIX for Dummies Questions & Answers

Executing nested loops+foreach

It's been a while since I used csh formatting and I am having a little bit of trouble with a few things. Things seem so much easier to execute in Matlab, however I need to do this on the terminal because of the programs I am trying to interact with. So here's what I want to do: I have a file... (0 Replies)
Discussion started by: katia
0 Replies

8. Shell Programming and Scripting

two while nested loops

for server in $(echo `cat /tmp/ScanHosts_${USERSNAME}.TXT`) do for portnumber in $(echo `cat /tmp/ScanPorts_${USERSNAME}.TXT`) do #echo ${server} ${portnumber} ... (3 Replies)
Discussion started by: SkySmart
3 Replies

9. Shell Programming and Scripting

ksh - Need Help Reducing Nested Loops

Hello, I pulled out some old code from an unfinished project the other day and wanted to stream line it better. I know anything beyond a double loop is usually bad practice, and I came up with some logic for later that would no longer require the first loop in the following code that works: ... (5 Replies)
Discussion started by: Azrael
5 Replies

10. UNIX for Beginners Questions & Answers

Nested Loops for text file

Hi A text file containing data something likeVehicle: BMW Class checkin_note: Tyre : Four path_id : 11 vault_file_size: -1 Vehicle: Toyota Class checkin_note: Tyre : Four path_id : 11 vault_file_size: -1 Vehicle: Chevrolet Class checkin_note: Tyre : Five path_id :... (7 Replies)
Discussion started by: vipinHasija
7 Replies
getopt(1)							   User Commands							 getopt(1)

NAME
getopt - parse command options SYNOPSIS
set -- ` getopt optstring $ * ` DESCRIPTION
The getopts command supersedes getopt. For more information, see NOTES below. getopt is used to break up options in command lines for easy parsing by shell procedures and to check for legal options. optstring is a string of recognized option letters; see getopt(3C). If a letter is followed by a colon (:), the option is expected to have an argument which may or may not be separated from it by white space. The special option - is used to delimit the end of the options. If it is used explicitly, getopt recognizes it; otherwise, getopt generates it; in either case, getopt places it at the end of the options. The posi- tional parameters ($1 $2 ...) of the shell are reset so that each option is preceded by a - and is in its own positional parameter; each option argument is also parsed into its own positional parameter. EXAMPLES
Example 1: Processing the arguments for a command The following code fragment shows how one might process the arguments for a command that can take the options -a or -b, as well as the option -o, which requires an argument: set -- `getopt abo: $*` if [ $? != 0 ] then echo $USAGE exit 2 fi for i in $* do case $i in -a | -b) FLAG=$i; shift;; -o) OARG=$2; shift 2;; --) shift; break;; esac done This code accepts any of the following as equivalent: cmd -aoarg filename1 filename2 cmd -a -o arg filename1 filename2 cmd -oarg -a filename1 filename2 cmd -a -oarg -- filename1 filename2 ATTRIBUTES
See attributes(5) for descriptions of the following attributes: +-----------------------------+-----------------------------+ | ATTRIBUTE TYPE | ATTRIBUTE VALUE | +-----------------------------+-----------------------------+ |Availability |SUNWcsu | +-----------------------------+-----------------------------+ |CSI |enabled | +-----------------------------+-----------------------------+ SEE ALSO
intro(1), getopts(1), getoptcvt(1), sh(1), shell_builtins(1), getopt(3C), attributes(5) DIAGNOSTICS
getopt prints an error message on the standard error when it encounters an option letter not included in optstring. NOTES
getopt will not be supported in the next major release. For this release a conversion tool has been provided, namely, getoptcvt. For more information, see getopts(1) and getoptcvt(1). Reset optind to 1 when rescanning the options. getopt does not support the part of Rule 8 of the command syntax standard (see intro(1)) that permits groups of option-arguments following an option to be separated by white space and quoted. For example, cmd -a -b -o "xxx z yy" filename is not handled correctly. To correct this deficiency, use the getopts command in place of getopt. If an option that takes an option-argument is followed by a value that is the same as one of the options listed in optstring (referring to the earlier EXAMPLES section, but using the following command line: cmd -o -a filename getopt always treats it as an option-argument to -o; it never recognizes -a as an option. For this case, the for loop in the example shifts past the filename argument. SunOS 5.10 7 Jan 2000 getopt(1)
All times are GMT -4. The time now is 04:04 AM.
Unix & Linux Forums Content Copyright 1993-2022. All Rights Reserved.
Privacy Policy