Login or Register to Ask a Question and Join Our Community

Sponsored Content
Full Discussion: quick question
Top Forums Shell Programming and Scripting quick question Post 66931 by S.Vishwanath on Friday 18th of March 2005 05:15:35 AM
Old 03-18-2005
Ya, as explained by Bhargav, it gives the return value of the Previous command.
In the above, when you run the jfdfkjd at the prompt, which is not a valid command, the system (shell) fired with command not found...and so when you immediately check $?, it give the return (exit status) of the previous command, and since the value is greater than 0, says that the previous command was an abnormal kind of operation.
Where as next time when data was executed, since its a valid command, it did work fine and hence when you immediately execute $? it return 0 saying that the previuos unix operation was a normal/smooth/perfect operation.

Even you can follow the similar decipline in your programming either C or Shell scripting (use exit 0 in shell script to indicate operationg was smooth else use exit <any greater than zero value> to indicate a failure operation.) This is a good dicipline programming approach.

Small Test, try this..at the command prompt prompt

abcd
echo $?
echo $?
ls
echo $?
echo $?
abcd
echo $?
echo $?
echo $?
-->All the best in your test.
 

10 More Discussions You Might Find Interesting

1. UNIX for Dummies Questions & Answers

Quick Question

I know in DOS, when you want to pull up your last/previous command, you hit the up/down arrows. How do you do that with UNIX? (3 Replies)
Discussion started by: Tracy Hunt
3 Replies

2. Shell Programming and Scripting

A very quick question

Just a super quick question: how do you put a link in your php code. I want to make a link to something in /tmp directory. i.e. how do you put a href into php, I think it's done a bit differently. thanks john (1 Reply)
Discussion started by: jmg5
1 Replies

3. UNIX for Dummies Questions & Answers

Quick Question

Hello There! I am trying to write this SIMPLE script in Bourne Shell but I keep on getting syntax errors. Can you see what I am doing wrong? I've done this before but I don't see the difference. I am simply trying to take the day of the week from our system and when the teachers sign on I want... (7 Replies)
Discussion started by: catbad
7 Replies

4. UNIX for Dummies Questions & Answers

Another quick question

Hi guys sed -e "s/$<//g" the $< can allow me to assign an input value to the variable right? do the double quotes check the previous context? (1 Reply)
Discussion started by: hamoudzz
1 Replies

5. UNIX for Dummies Questions & Answers

Quick Question

Hi, I am new to UNIX, and am learning from this tutorial : http://www.ee.surrey.ac.uk/Teaching/Unix/index.html It keeps telling me to files downloaded from the internet (like .txt files) to the directory, and I dont know how to. How do I add .txt files to my directory? Thanks. (6 Replies)
Discussion started by: IAMTHEEVILBEAN
6 Replies

6. UNIX for Dummies Questions & Answers

Quick question

Hi, Is there a simple way, using ksh, to find the byte position in a file that a stated character appears? Many thanks Helen (2 Replies)
Discussion started by: Bab00shka
2 Replies

7. UNIX for Dummies Questions & Answers

quick question

from command prompt I did grep two words on a same line for eg: grep abc | grep xyz and I got tht particular line, but I want to know when I vi that file how to directly search for that particular line? I appreciate if any one can provide answer, thanks in advance (2 Replies)
Discussion started by: pkolishetty
2 Replies

8. UNIX for Dummies Questions & Answers

Quick question

Hello all, Quick question from a fairly new to Unix developer. if then completedLogFile=$logfile.$(date +%Y%m%d-%H:%M:%S) mv $logfile $completedLogFile fi I understand that this portion of code is simply copying a tmp logfile to a completed logfile when a condition is true. The... (2 Replies)
Discussion started by: JohnnyBoy
2 Replies

9. UNIX for Dummies Questions & Answers

Quick question.

I'd like to list all userid's on the system that have a .bashrc file in their home directory with a command like "cat /etc/passwd | grep -f", however I'm not quite familiar with using grep. Any suggestions? (2 Replies)
Discussion started by: raidkridley
2 Replies

10. Shell Programming and Scripting

Quick question

When I have a file like this: 0084AF aj-123-a NAME Ajay NAME Kumar Engineer 015ED6 ck-345-c 020B25 ef-456-e 027458 pq-890-p NAME Peter NAME Salob Doctor 0318F0 xy-123-x NAME Xavier Arul NAME Yesu Supervisor 0344CA de-456-d where - The first NAME is followed by... (6 Replies)
Discussion started by: ajay41aj
6 Replies

LEARN ABOUT DEBIAN

platform::shell

platform::shell(3tcl)					       Tcl Bundled Packages					     platform::shell(3tcl)

__________________________________________________________________________________________________________________________________________________

NAME

       platform::shell - System identification support code and utilities

SYNOPSIS

       package require platform::shell ?1.1.4?

       platform::shell::generic shell
       platform::shell::identify shell
       platform::shell::platform shell
_________________________________________________________________

DESCRIPTION

       The platform::shell package provides several utility commands useful for the identification of the architecture of a specific Tcl shell.

       This  package  allows the identification of the architecture of a specific Tcl shell different from the shell running the package. The only
       requirement is that the other shell (identified by its path), is actually executable on the current machine.

       While for most platform this means that the architecture of the interrogated shell is identical to the architecture of  the  running  shell
       this  is  not generally true. A counter example are all platforms which have 32 and 64 bit variants and where a 64bit system is able to run
       32bit code. For these running and interrogated shell may have different 32/64 bit settings and thus different identifiers.

       For applications like a code repository it is important to identify the architecture of the shell which will  actually  run  the  installed
       packages, versus the architecture of the shell running the repository software.

COMMANDS

       platform::shell::identify shell
	      This command does the same identification as platform::identify, for the specified Tcl shell, in contrast to the running shell.

       platform::shell::generic shell
	      This command does the same identification as platform::generic, for the specified Tcl shell, in contrast to the running shell.

       platform::shell::platform shell
	      This command returns the contents of tcl_platform(platform) for the specified Tcl shell.

KEYWORDS

       operating system, cpu architecture, platform, architecture

platform::shell 						       1.1.4						     platform::shell(3tcl)
All times are GMT -4. The time now is 02:13 PM.
Unix & Linux Forums Content Copyright 1993-2022. All Rights Reserved.
Privacy Policy