shell problem

Thread Tools Search this Thread
Top Forums UNIX for Dummies Questions & Answers shell problem
# 1  
Old 09-09-2001
Question shell problem

[ "$DEBUG" = Y ] && set -x && echo "enter tablespace_end_backup" >&2

Can you tell me what's mean above?

# 2  
Old 09-10-2001
Well when two commands are linked together by && the second one is executed only if the first succeeds. So something like:

[ $DEBUG = y ] && echo DEBUG is set >&2

will echo "DEBUG is set" if and only if $DEBUG is equal to y. It's a one line "if" statement. The >&2 sends the output of the echo to stderr rather than stdout.

"set -x" will always succeed. So the second && is a way to do two statements based on the results of the first test. I think it's poor syntax and I would use:

[ "$DEBUG" = Y ] && { set -x ; echo "enter tablespace_end_backup" >&2 ; }

Of course, you can strongly argue for a full "if" statement in this case, but many programmers (including me) try to keep debug statements to one like so they can easily be commented out to improve performance.
Login or Register to Ask a Question

Previous Thread | Next Thread

10 More Discussions You Might Find Interesting

1. UNIX for Dummies Questions & Answers

shell problem

this picture for print You didn't do the question. Go back. if $1 = 0 but until now it give me this message what i should be do ? (2 Replies)
Discussion started by: NeeZaaR
2 Replies

2. Shell Programming and Scripting

shell problem

problem: I give the source of a c program.. is required to indicate how many times is called each function defined in the program and line number there is a call. let's say i have lab2.c: float dist(int *a,int *b,int n){ int i=0; double d=0; for (i=1;i<=n;i++){ d+=pow((a-b),2); }... (4 Replies)
Discussion started by: sherpeledenis
4 Replies

3. Shell Programming and Scripting

Problem in shell script

hi...i create a script which reads data from file and compare that the data which is entered by me through keyboard...i can easily read first two contents of file..i am facing the problem to read other contents.. structure of my file is username:password:username1:password1.......and so on ... (1 Reply)
Discussion started by: shubhig15
1 Replies

4. Shell Programming and Scripting

shell problem

Hello! Can you please help me on a lab at school: I have to to write a shell program which reads all .C files from the current directory and prints for each file how many '#define' directives it has and for each macro defined how many times is it used in that file. Can you suggest how can i... (1 Reply)
Discussion started by: dark_knight
1 Replies

5. Shell Programming and Scripting

problem with if in shell

Hi, My sheel script has below statement: if; then When I run iam getting the below error: -bash: syntax error near unexpected token `then' What is wrong with that statement: Plz help me. (2 Replies)
Discussion started by: pradeep_script
2 Replies

6. Shell Programming and Scripting

Shell Problem

Hi all, until yesturday grep command was running in KSH .... I was executing this command ls -l | grep *.sh But today its not working at all ... Should I check any of the setting ... I am not getting whats the problem ... I have relogged to unix box but it didn't... (14 Replies)
Discussion started by: dhananjayk
14 Replies

7. Shell Programming and Scripting

Problem in shell

hi, can any one tell a solution for the following : I want to append 10 spaces and a string say "ok" to 12 digit number which is stored in a varialbe & display using shell script. (1 Reply)
Discussion started by: Sandeep Kale
1 Replies

8. UNIX for Dummies Questions & Answers

shell problem

What are the different type of shell available in UNIX and how to change the shell? just this 2 question pls help mi (4 Replies)
Discussion started by: yeah016
4 Replies

9. UNIX for Advanced & Expert Users

Shell Problem

Dear Members; I changed ,by mistake ,the root shell in /etc/passwd and logged out. Thereafter, I can no more have a prompt when trynig to log in as root. How to solve this pb ? Regards :confused: (8 Replies)
Discussion started by: oss
8 Replies

10. UNIX for Dummies Questions & Answers

Shell Problem.

Hello and Good day to all. Im having a problem here and would like to know if there is any solution that could overcome my problem. I have changed from bash to csh (c-shell) yesterday on my Linux 7.2. When i do $echo $SHELL i can see the output /bin/csh which means ihave succesfully landed on... (4 Replies)
Discussion started by: ###1tomato
4 Replies
Login or Register to Ask a Question