Visit Our UNIX and Linux User Community

Question about variables

Thread Tools Search this Thread
Top Forums Shell Programming and Scripting Question about variables
# 1  
Old 11-11-2009
Question about variables

What does this mean?

BACKUPFILE=backup-$(date +%m-%d-%Y)

Last edited by pludi; 11-11-2009 at 04:37 PM.. Reason: code tags, please...
# 2  
Old 11-11-2009
The variable archive gets set to $1 if it exists otherwise if get set to "backup-$(date +%m-%d-%Y) (e.g. "backup.10-29-2009")
# 3  
Old 11-11-2009
i would suggest reading up on bash parameter substitution... It's comes in really handy if you have to do a lot of manipulation with a single variable otherwise you have to add on a bunch of test logic.
# 4  
Old 11-11-2009
Your question(s) could easily be answered by searching the Internet with Google. Google is your friend Smilie

Have a read of these links:

Shell expansion

Operations on variables

# 5  
Old 11-11-2009

Previous Thread | Next Thread
Test Your Knowledge in Computers #487
Difficulty: Easy
A program's entry point is always defined by a main function or method.
True or False?

10 More Discussions You Might Find Interesting

1. UNIX for Dummies Questions & Answers

Question On Sourcing Variables

I have 2 scripts first script would call second script. #!/bin/bash logfile=`basename $0`.log echo "First File" >> $logfile TIME=`ls -lu array.ksh | awk '{print $6" "$7" "$8}'` . /home/infrmtca/bin/Test/ #/home/infrmtca/bin/Test/ #!/bin/bash... (1 Reply)
Discussion started by: Ariean
1 Replies

2. Shell Programming and Scripting

awk question for printing variables

Hi All, I have the following awk code where I am passing 4 variables to the program and I need to print them in the awk script. The variables are $start_month $start_date - $end_month $end_date. printf("\tFor More Information\n") > out_tmp1 printf("\tIf you have any questions about this... (6 Replies)
Discussion started by: nua7
6 Replies

3. Programming

Question on integer variables (c++)

Hello guys! It's orszhak and in my book I am currently studying incrementing values in c++ and it states thant I could do this to increment the value of nVariable nVariable = nVariable + 2; it states that I could also do this and assign the same value nVariable += 2; but can't I also do this and... (1 Reply)
Discussion started by: orszhak
1 Replies

4. UNIX for Dummies Questions & Answers

Variables question

Hi I am trying to find were to look for definitions of these variables; $0, $1, $2, $#, $$ , $*. I am not having much luck with my searching. Can anyone point me in the right direction? Thanks, Doug (3 Replies)
Discussion started by: Reddoug
3 Replies

5. Linux

Question about Variables in If?

Hi everybody, im trying to store a path "address" of a file in a variable, then IF the Address that the user entered INSIDE the variable is exist, do something, else echo invalid file address. here's my code, but it's not working i dunno why: $variable cat > variable #variable will contain... (4 Replies)
Discussion started by: iam_ako
4 Replies

6. Shell Programming and Scripting

question about variables with sed

Hi, I am trying to do some mass replacements in lots of scripts, and using sed. However sed doesn't seem to like to be able to dereference variables within the substitute clause. For example: tab=newtable cat f1 | sed 's/oldtable/$tab/g' doesn't work. it would replace oldtable with the... (2 Replies)
Discussion started by: fwellers
2 Replies

7. UNIX for Dummies Questions & Answers

Shell script question on variables

I have the following script that is supposed to calculate the runtime of the script as a whole (edited for brevity): #!/bin/sh # set endtime and print elapsed time set starttime=`date +%s` echo "Value of starttime: " $starttime sleep 1 set endtime=`date +%s` echo "Value of endtime: "... (2 Replies)
Discussion started by: figaro
2 Replies

8. UNIX for Dummies Questions & Answers

Question about variables

I am looking for 8 variables in the following profile. I am looking to see if anyone could explain this for me better than the book I am using has been able to. There are 5 system, 2 aliases, and one editor. The profile is as follows: # @(#)local.profile 1.8 99/03/26 SMI stty istrip... (0 Replies)
Discussion started by: wswaner
0 Replies

9. Programming

A question on C programming and Outputing variables

I was wondering if someone could show me what I'd need to do in C programming language to output the current values of all of your environment variables and do so in such a way that it will duplicate an "env" command on unix. Does anyone know how and can you share it with me? Thanks in advance. (2 Replies)
Discussion started by: HelpMeIAmLost
2 Replies

10. Shell Programming and Scripting

Question variables Korn

I'm using the following command to test for certain characters in a script echo "${1}" | grep '\$' if (( ${?} == 0 )) then testing this script on the command line I have ksh -x "xxxx$xxxx" this works fine but when I want to use ksh -x "xxxx $xxx" the... (1 Reply)
Discussion started by: frank
1 Replies

Featured Tech Videos