Login or Register to Ask a Question and Join Our Community

Sponsored Content
Full Discussion: Compare 2 strings
Operating Systems Linux Ubuntu Compare 2 strings Post 303032806 by wisecracker on Sunday 24th of March 2019 12:41:36 PM
Old 03-24-2019
You are jumping the gun at the moment; UNDERSTAND what is going on first!

I mentioned that there is a FLAW. Try to understand that when messing with HW you need to know what you are doing.
Read the URL and understand to get a grasp of what is going on; although the code will work 99.999% of the time there is a condition known as a "race condition".
Race condition - Wikipedia

Although not strictly a race condition it is a _pseudo_race condition.

An explanation:
If you move the mouse a tiny fraction of a second AFTER the 'if' line and before the condition is finalised then the two variables will be the same.
Assuming you have this _polling_ as you put it in a loop then this will be missed on the second variable and the next time in the loop the two values will be the same again and so it will seem no-one has moved the mouse. This, although NOT strictly a race condition per-se is close enough.
AFAIAC there is no easy cure using sequential code like a shell script so you HAVE to be aware of such situations.

So be aware; it is these subtleties that can cause headaches in the future.

As for _polling_ you could put the code inside a 'while' loop, while true and exit the loop via a break command using the conditional statement if that is what you want.
 

10 More Discussions You Might Find Interesting

1. Shell Programming and Scripting

to compare two strings

hi all, i am new to unix. Actually i need to compare two string and print the result... suppose type='sun' if; then echo good morning else echo good night fi whether the comparison is right r we need to use eq???? help me please.... :confused: thanks in advance.... (1 Reply)
Discussion started by: ithirak17
1 Replies

2. Shell Programming and Scripting

How to compare two strings

Hi all, I am trying to compare two strings/dates, but its throwing error::Syntax error at line 5: Please help !! Any alternate way to compare two dates is also fine.... logdate1=`date -u '+%Y.%m.%d %T'` sleep 5 logdate2=`date -u '+%Y.%m.%d %T'` if test... (5 Replies)
Discussion started by: prashant43
5 Replies

3. Shell Programming and Scripting

How to compare two strings using if

Hi, Here is my script #!/bin/ksh echo $pick_typ if ];then echo "inside if" else echo "outside if" fi when ever i pass CUS as parameter to this script am getting the correct value CUS, however if i pass ORD as parameter it is not coming inside if it is echoing else "Outside... (12 Replies)
Discussion started by: bhargav20
12 Replies

4. Shell Programming and Scripting

Compare text strings.

Hi Im trying to write a script that compare a text string. But it fails, I think it adds a extra line feed to the result and fails beacuse of that. The script. DT=`date +'%Y%m%d%H%M%S'` #ALARM_BIN=/users/alarms/ssa/alarms/bin QUEUE_THR=10 #unset offset #offset="***Server reports data... (3 Replies)
Discussion started by: vettec3
3 Replies

5. Shell Programming and Scripting

How to Compare 2 Strings ?

Hello , I want to Compare with 2 strings and get if they are True or not please would like some help on this #!bin/ksh echo "Enter Name 1" read Name1 echo "Enter Name 2" read Name2 echo "------------------------" echo "First Name: $Name1" echo "Second Name: $Name2" echo... (25 Replies)
Discussion started by: shatztal
25 Replies

6. Shell Programming and Scripting

Compare two strings

hi.. i have a problem to compare two string my code is like that if ] then echo "both data are correct" elif ] echo "data is wrong" fi here $username1 is taking value from file.. (7 Replies)
Discussion started by: shubhig15
7 Replies

7. Shell Programming and Scripting

How to compare two strings in a file

hello guyzz please help me out.. I have two file a.sh and b.sh it contains two string SD109 ,SD108 . I want to compaere these two string . If a.sh>b.sh do rebasing record time. else it shows no rebasing required. Thanks. (2 Replies)
Discussion started by: abhijtr
2 Replies

8. Shell Programming and Scripting

Compare strings with space in if statement

DEV> vi test_if_statement.sh "test_if_statement.sh" 9 lines, 205 characters proc_out="Normal completion" proc_out_comp="Normal completion" echo 'proc_out:'$proc_out echo 'proc_out_comp:'$proc_out_comp if then echo 'match' else echo 'no_match' fi ~ ~ ~ ~ ~ ~ ~ ~ ~ (4 Replies)
Discussion started by: cartrider
4 Replies

9. Shell Programming and Scripting

Compare 2 Strings

I have 2 values V_1_4_4_b1 and V_1_5_1_RC_b1. I would need to compare them and determine if the 1st value is greater, less or equal than the 2nd value. The result should need to have a return value. I have below code in bash function but it seems it is not comparing it correctly. Any help will... (8 Replies)
Discussion started by: aderamos12
8 Replies

10. UNIX for Beginners Questions & Answers

If statement to compare two strings

Hi, I am trying to do the following to see if "ip" is already present in a file. if ; then echo "hi" else echo "hello" fi I am seeing errors on the if statement. Can someone please correct the syntax for me? Thanks (2 Replies)
Discussion started by: waince
2 Replies

LEARN ABOUT DEBIAN

check-symbols

CHECK-SYMBOLS(1)					      General Commands Manual						  CHECK-SYMBOLS(1)

NAME

       check-symbols - verify symbols exported by a new library version

SYNOPSIS

       check-symbols <source-package> [DEBDIR]

DESCRIPTION

       To  verify the symbols exported by a new library version, run check-symbols with the name of the source package as argument.  check-symbols
       will first determine the symbols exported by the existing and installed library version, then install the new library and compare the  sym-
       bols  exported  by the new library version with the symbols exported by the old version.  For each of the symbols found, check-symbols will
       list if the symbol is new, unchanged or has been removed in the new library version.

       In case the source package contains multiple binary library packages, all library files in each of the binary packages will be verified.

       check-symbols uses nm -D to determine the exported symbols of the libraries.

       If no value is given for DEBDIR, the script will assume the new library deb files are stored in /var/cache/pbuilder/result.

EXAMPLES

       check-symbols telepathy-glib .

       This will:

	 o Use nm -D to determine the exported symbols of the old,
	   installed versions of the libraries provided by telepathy-glib.

	 o Install the binary libraries provided by the new version of
	   telepathy-glib.

	 o Compare the output of nm -D of the new libraries with the
	   output of the old version.

	 o List the result in diff format.

BUGS

       Please report bugs on:
       https://bugs.launchpad.net/ubuntu/+source/ubuntu-dev-tools/

SEE ALSO

       nm(1)

AUTHOR

       check-symbols was written by Daniel Holbach <daniel.holbach@ubuntu.com> and this manpage by Albert Damen <albrt@gmx.net>. Both are licensed
       under the GNU General Public License, version 2.

ubuntu-dev-tools						 December 9, 2007						  CHECK-SYMBOLS(1)
All times are GMT -4. The time now is 05:21 AM.
Unix & Linux Forums Content Copyright 1993-2022. All Rights Reserved.
Privacy Policy