Sponsored Content
Full Discussion: Variable definition
Top Forums UNIX for Advanced & Expert Users Variable definition Post 302874085 by greet_sed on Thursday 14th of November 2013 05:26:15 AM
Old 11-14-2013
See here

Example shows how it works :
Code:
A=30
B=40
echo ${A:-B} 
30
A=""
echo ${A:-B}
B
echo {A:-$B}
{A:-40}

 

10 More Discussions You Might Find Interesting

1. UNIX for Dummies Questions & Answers

Definition of Concurrent Users

Can someone guide me in telling me what is a good definition of concurrent users. Is there a website I can go to to get this definition? (2 Replies)
Discussion started by: mpshaw
2 Replies

2. Shell Programming and Scripting

What wrong with the variable definition

i am using the below script and trying to move files in that directory in that pattern to archive. But it doesn;t seem to take the metacharacters. Please sugggest. Code Debug output: (1 Reply)
Discussion started by: dsravan
1 Replies

3. Shell Programming and Scripting

daemons definition

hi there, can somebody give me a definition for daemons, or example what are they !! and what the use for? i've done some research and all what i found is /etc/... or /usr/bin/... and i haven't quietly got the concept. any ideas !! Thanks. (5 Replies)
Discussion started by: new2Linux
5 Replies

4. UNIX for Dummies Questions & Answers

Definition of $-

Could someone please direct me to a link that gives the definitions for each of the letters from the results of the $- environment variable? It would be nice to know what shell options each of the letters represents, but I am specifically looking for the shell option for 'c' (lowercase c). Thank... (12 Replies)
Discussion started by: sszd
12 Replies

5. Shell Programming and Scripting

How to define a variable with variable definition is stored in a variable?

Hi all, I have a variable say var1 (output from somewhere, which I can't change)which store something like this: echo $var1 name=fred age=25 address="123 abc" password=pass1234 how can I make the variable $name, $age, $address and $password contain the info? I mean do this in a... (1 Reply)
Discussion started by: freddy1228
1 Replies

6. HP-UX

macro definition in FTP

Hi, I am trying to create a macro in FTP to rename multiple files.Below given is the codewhich i tried. I wanted to pass the files from the file "$FTPTXRENAMESUCLIST`" to the renfiles macro. Your help will be really appreciated. ftp -i -v -n << endftp > $FTPTXLOG 2> $FTPER open... (0 Replies)
Discussion started by: tinivt
0 Replies

7. What is on Your Mind?

Definition of Bytes

A byte is the smallest unit of storage which can be accessed in a computer's memory- either in RAM or ROM.It also holds exactly 8 bits.But its old view one byte was sufficient to hold one 8 bit character.Modern days especially on .NET or international versions of Win 32, 16 bits is needed. ... (2 Replies)
Discussion started by: stoudtLion
2 Replies

8. Programming

Get struct definition

I have many headers with huge amount of structures in them, typical one looks like this: $ cat a.h struct Rec1 { int f1; int f2; }; struct Rec2 { char r1; char r2; }; struct Rec3 { int f1; float k1; float ... (6 Replies)
Discussion started by: migurus
6 Replies

9. UNIX for Dummies Questions & Answers

Environment variable definition

I'm a bit confused about the term ‘environment variables'. Within your shell you can set two types of variables: 1. Shell variable - affecting functionality within your shell 2. User defined variable When using the ‘export' command on a variable you make sure it's being inherited by new sub... (2 Replies)
Discussion started by: niels
2 Replies

10. UNIX for Beginners Questions & Answers

Variable definition inside mysql query

Hello, I am running ubuntu16.04. By means of @Rudic's help, I have below command. What I need to do is to replace video_id by value of video_id in which WHERE clause is matched: {print "INSERT INTO video_series_files (id, video_id, file_type, protocol, \ url, languages, quality, accessed... (12 Replies)
Discussion started by: baris35
12 Replies
OPEN(1) 							     Linux 1.x								   OPEN(1)

NAME
open - start a program on a new virtual terminal (VT). SYNOPSIS
open [-c vtnumber] [-s] [-u] [-l] [-v] [--] command command_options DESCRIPTION
open will find the first available VT, and run on it the given command with the given command options, standard input, output and error are directed to that terminal. The current search path ($PATH) is used to find the requested command. If no command is specified then the envi- ronment variable $SHELL is used. OPTIONS -c vtnumber Use the given VT number and not the first available. Note you must have write access to the supplied VT for this to work. -s Switch to the new VT when starting the command. The VT of the new command will be made the new current VT. -u Figure out the owner of the current VT, and run login as that user. Suitable to be called by init. Shouldn't be used with -c or -l. -l Make the command a login shell. A - is prepended to the name of the command to be executed. -v Be a bit more verbose. -w wait for command to complete. If -w and -s are used together then open will switch back to the controlling terminal when the command completes. -- end of options to open. NOTE
If open is compiled with a POSIX (Gnu) getopt() and you wish to set options to the command to be run, then you must supply the end of options -- flag before the command. EXAMPLES
open can be used to start a shell on the next free VT, by using the command: open bash To start the shell as a login shell, use: open -l bash To get a long listing you must supply the -- separator: open -- ls -l SEE ALSO
login(1), doshell(8), switchto(1). AUTHOR
Jon Tombs <jon@gtex02.us.es or jon@robots.ox.ac.uk> -w idea from "sam". 19 Jul 1996 V1.4 OPEN(1)
All times are GMT -4. The time now is 05:46 PM.
Unix & Linux Forums Content Copyright 1993-2022. All Rights Reserved.
Privacy Policy