Aa_app varible in Linux


 
Thread Tools Search this Thread
Top Forums UNIX for Dummies Questions & Answers Aa_app varible in Linux
# 1  
Old 05-06-2015
Aa_app varible in Linux

Hi,

I am analyzing linux script, below is the following script line

Code:
 
${AA_APP:-/opt/ty/aa}/sbin/save_file_list ApplEnv.prererun ${AA_APP:-/opt/ty/aa}/sbin/ApplEnv.install_save_list

I really dont understand what this line does, can someone explain me.


AA_APP is variable assigning /opt/ty/aa directory?
# 2  
Old 05-06-2015
man bash:
Quote:
${parameter:-word}
Use Default Values. If parameter is unset or null, the expansion of word is substituted. Otherwise, the value of parameter is substituted.
This User Gave Thanks to RudiC For This Post:
# 3  
Old 05-06-2015
Thanks, but still I dont understand does. why they are using two shell parameter. when I run this, its creating some file. but not getting exactly.

is it possible to explain me?
# 4  
Old 05-06-2015
Run command save_file_list from $AA_APP/sbin/ or, if AA_APP is NULL or unset, from /opt/ty/aa/sbin/ with first parameter ApplEnv.prererun and second parameter ${AA_APP}/sbin/ApplEnv.install_save_list or, if AA_APP is NULL or unset, /opt/ty/aa/sbin/ApplEnv.install_save_list. It looks to me as if the second par. might be a program to be run from within the command...
# 5  
Old 05-06-2015
Code:
${AA_APP:-/opt/ty/aa}/sbin/save_file_list......

AA_APP=/usr/share
Now the path would lead to /usr/share/sbin/save_file_list....
AA_APP=""
Now the path would lead to: /opt/ty/aa/sbin/save_file_list...

But saving a 'save_file_list' in a(ny) sbin path, isnt the best idea any way.

hth

Last edited by sea; 05-06-2015 at 01:52 PM..
 
Login or Register to Ask a Question

Previous Thread | Next Thread

10 More Discussions You Might Find Interesting

1. Shell Programming and Scripting

awk - how to pass varible

I want to pass variable to below awk statement awk '/abc123/{x=NR+1}(NR<=x){print}' sftp_log_20150317.log I tried -v like below, but its not working. Please help!!! awk -v var1="abc123" '/var1/{x=NR+1}(NR<=x){print}' sftp_log_20150317.log Input file is: sftp_log_20150317.log ... (3 Replies)
Discussion started by: vegasluxor
3 Replies

2. Shell Programming and Scripting

Setting Varible with AWK in KSH

I am trying to set a variable from this AWK command in KSH but I keep getting an error that says my variable cannot be found. LOADNO = $(awk -F"|" 'NR==1{print $2}' file.txt) If I just run awk -F"|" 'NR==1{print $2}' file.txt I get the right value but as soon as I try to assign this... (1 Reply)
Discussion started by: cvigeant
1 Replies

3. UNIX for Dummies Questions & Answers

How to store/read multiple values from a varible

Hi, when I enter 'ps -ef| grep process_name'/'psu | grep process_name', i am getting multiple number of lines output( i mean multiple no of processes).how can i store it one by one and echo it in the same way(one by one). part of script is var1=$(remsh hostname -l username ps -ef|grep... (2 Replies)
Discussion started by: jeanzibbin
2 Replies

4. Shell Programming and Scripting

BASH Varible nesting and user input

Well, I think I've managed to take two different issues and conglomerate them into and embarrasing mess. #!/bin/bash # Set some variables dir1=/path/that/isnt/variable/$variabledir/dir/ dir2=/path/that/isnt/variable/$variabledir/important/"$variabledir"-subdirectory/path/ echo "Gimme... (7 Replies)
Discussion started by: karlp
7 Replies

5. Shell Programming and Scripting

Perl: varible-sized arrays?

How do you store strings in a variable-sized array? Background: I wrote a program earlier today to work with a very large text file. I chose Perl because it lets me do some nice formatting on the text I grab, instead of just using a shell script to con'cat'enate egrep results. The program... (2 Replies)
Discussion started by: CRGreathouse
2 Replies

6. UNIX for Dummies Questions & Answers

Is this a varible type?

Wondering what $@ does - is it a variable of some kind? (1 Reply)
Discussion started by: Jayden
1 Replies

7. Shell Programming and Scripting

Space in varible?

Hey guys I have here what I am sure amounts to a pretty dumb question.... how do I assign a value of say 999 to a variable called "random number" (note the space between random and number). What would the script look like using borne shell? Thanks! :) (4 Replies)
Discussion started by: pattingtonjbear
4 Replies

8. Shell Programming and Scripting

How to write a varible into file in ksh

set filename $logDir/PyLog/$logname echo $filename >> logname.txt I am trying to write to write the varibale filename into a file logname.txt,it is not working could any one suggest y (2 Replies)
Discussion started by: nathgopi214
2 Replies

9. Shell Programming and Scripting

chaging a environment varible using sheel script

hi How can one change an environment varaible inside a shell script say my bash shell has a env variable export FOO="Day" no i want to write a script inside which the FOO variable is modified to say export FOO=NIGHT after this script finishes te bash shell should show me NIGHT when i... (1 Reply)
Discussion started by: wojtyla
1 Replies

10. Shell Programming and Scripting

Using varible/varible substitution in Perl/sed Search & Replace

Hi, I have a program that searches for a particular string patten. I am however having difficulty passing the varible $i (in a loop) as the string pattern to replace. Using either perl or sed search and replace statements, I get the same kinda result. For example, using the perl: for i in... (3 Replies)
Discussion started by: Breen
3 Replies
Login or Register to Ask a Question