Assigning variables Post: 302766639

Login or Register to Ask a Question and Join Our Community

Sponsored Content

Top Forums Shell Programming and Scripting Assigning variables Post 302766639 by Scrutinizer on Tuesday 5th of February 2013 05:42:14 AM

Old

02-05-2013

Moderator

eval is a two-stage operation, it first concatenates the arguments with spaces in between and then executes the resulting command. The backslash is there to keep the first $-sign from being evaluated before the concatenation phase. The backslash gets removed before the second phase.

If a user is able to control what is in variable $WMD_UPHASE4 then he could have his code executed with the permissions of the user executing the script.

A better approach would be the use of arrays. In ksh93 and bash4 that can be associative arrays, which means you could use words as the array index instead of only numbers..

Last edited by Scrutinizer; 02-05-2013 at 07:02 AM..

This User Gave Thanks to Scrutinizer For This Post:

Scrutinizer

View Public Profile for Scrutinizer

Find all posts by Scrutinizer

9 More Discussions You Might Find Interesting

1. UNIX for Dummies Questions & Answers

assigning variables

Before I even attempt this, is it possible to grep for a pattern, maybe a partial sentence like "go to page 3", assign that to a variable and then use awk or something to pull out the 3 and assign it to a variable? So first I would have Gotopg = "go to page 3" then page = 3

2. Shell Programming and Scripting

assigning variables in sed command

I need to assign a variable within a variable in a sed command. I tried doing the following in c shell. set left = 1 set right = 2 set segment = qwerty sed -n -e "/$segment{$left}/,/$segment{$right}/p" file.txt what is wrong with this syntax?

3. UNIX for Advanced & Expert Users

assigning variables to their defaults

Hi, Is there any way to assign defaults values to the shell variables without reassigning them ( restarting the session) for example after login the value of ORACLE_HOME=/a/b/c i have changed this value from the console export ORACLE_HOME=/c/d now what if i want the value exported to...

4. Shell Programming and Scripting

variables not assigning in a function

Hi GUYS, I have function. I am assigning a line count to count variable. But it is throwing an error at this line. function_recur (){ #file being created in this function lenth = `wc -l function_outpu.dat`; echo $lenth; } this is the error i got rec.ksh: lenth: not found. ...

5. UNIX for Dummies Questions & Answers

Assigning variables using awk

Hi, I am having a line which is separated by - I need to extract each field and put into some variable. a=`echo "this-is-the-case" | awk -F- '{print $1}' ` b=`echo "this-is-the-case" | awk -F- '{print $2}' ` c=`echo "this-is-the-case" | awk -F- '{print $3}' ` d=`echo "this-is-the-case" | awk...

6. Shell Programming and Scripting

Assigning expression value to tcsh variables

Hi All, I have a tcsh script as: #!/usr/bin/csh -x set packsName=$(awk -F'' '/^execute.*=true/{print $2}' ExecutePacks.config) for var in $packsName do echo "printed $var" done I want to assign the value which is returned by awk function to the variable called packsName. How do I...

7. Shell Programming and Scripting

Help with reading and assigning variables

Hi Gurus, I have a file named log with 2 lines Each line is a file name. eg $ cat log monday tuesday I need to read log and assign each output(filename) to a different variable. The following doesn't work:- while read A B do echo " a is ${A} " echo " b is ${B} " done <...

8. Shell Programming and Scripting

Help in assigning values to variables from the file

Hi! This might be a simple thing, but I'm struggling to assign values to variables from the file. I've the following values stored in the file.. It consists of only two rows.. 10 20 I want to assign the first row value to variable "n1" and the second row value to variable "n2".. That is ...

9. Shell Programming and Scripting

Assigning Variables

Hi, Can the below be clarified please. i just want to know what is the difference between the two ways of assigning variables as mentioned below. export SRC_TBL=${SRC_TBL-"MMA_COPAY_PLN_FACT_STG"} export SRC_TBL="MMA_COPAY_PLN_FACT_STG" thanks in advance :) Arun

LEARN ABOUT DEBIAN

bup-margin

bup-margin(1)						      General Commands Manual						     bup-margin(1)

NAME

       bup-margin - figure out your deduplication safety margin

SYNOPSIS

       bup margin [options...]

DESCRIPTION

       bup margin  iterates  through  all  objects  in	your  bup repository, calculating the largest number of prefix bits shared between any two
       entries.  This number, n, identifies the longest subset of SHA-1 you could use and still encounter a collision between your object ids.

       For example, one system that was tested had a collection of 11 million objects (70 GB), and bup margin returned 45.  That  means  a  46-bit
       hash  would be sufficient to avoid all collisions among that set of objects; each object in that repository could be uniquely identified by
       its first 46 bits.

       The number of bits needed seems to increase by about 1 or 2 for every doubling of the number of objects.  Since SHA-1 hashes have 160 bits,
       that  leaves 115 bits of margin.  Of course, because SHA-1 hashes are essentially random, it's theoretically possible to use many more bits
       with far fewer objects.

       If you're paranoid about the possibility of SHA-1 collisions, you can monitor your repository by running bup margin occasionally to see	if
       you're getting dangerously close to 160 bits.

OPTIONS

       --predict
	      Guess  the offset into each index file where a particular object will appear, and report the maximum deviation of the correct answer
	      from the guess.  This is potentially useful for tuning an interpolation search algorithm.

       --ignore-midx
	      don't use .midx files, use only .idx files.  This is only really useful when used with --predict.

EXAMPLE

	      $ bup margin
	      Reading indexes: 100.00% (1612581/1612581), done.
	      40
	      40 matching prefix bits
	      1.94 bits per doubling
	      120 bits (61.86 doublings) remaining
	      4.19338e+18 times larger is possible

	      Everyone on earth could have 625878182 data sets
	      like yours, all in one repository, and we would
	      expect 1 object collision.

	      $ bup margin --predict
	      PackIdxList: using 1 index.
	      Reading indexes: 100.00% (1612581/1612581), done.
	      915 of 1612581 (0.057%)

SEE ALSO

       bup-midx(1), bup-save(1)

BUP

       Part of the bup(1) suite.

AUTHORS

       Avery Pennarun <apenwarr@gmail.com>.

Bup unknown-															     bup-margin(1)