05-21-2009
How to check if a command returns nothing
Hi, I want to write a script that runs a command (at -l) and writes the output to a file. If the command (at -l) command returns no value (is empty/null) then write a message to the file in place of the command output.
My problem is around trapping the empty returned command value and replacing with my own message. Checking $? returns success (0) as the command ran but the return from the command is empty.
Appreciate any help, thanks.
10 More Discussions You Might Find Interesting
1. UNIX for Dummies Questions & Answers
This is my list of sed commands: can anyone tell me where im going wrong. The script works on a file called data which contains 6 student id's and there answers for 6 questions.
!/bin/sh
sed -e 's/*//g' \ #replace * with nothing
-e s/ /X/g' \ #replacing empty space with X
-e... (2 Replies)
Discussion started by: jeffersno1
2 Replies
2. UNIX for Dummies Questions & Answers
When I do the following command where jxh777 is my userid to see my processes, I see a question mark in the return. Does that mean anything ?
ps -ef | grep jxh777
jxh777 9966 9965 0 16:47:46 pts/tb 0:00 -ksh
jxh777 11660 9966 1 17:05:02 pts/tb 0:00 grep jhabi0
jxh777 28162 28160... (6 Replies)
Discussion started by: jxh461
6 Replies
3. UNIX for Dummies Questions & Answers
Hi guys.
I am trying, to move files found with the find command...
Script runs fine, until it reaches a file that contains spaces...
Here is what i wrote up quickly.
ROOTDIR=/apps/data
SEARCH=$(find /data/HDTMPRestore/home/tmq/ -type f -print | grep Mods/Input/bck | cut -c19-)
for i... (1 Reply)
Discussion started by: Stephan
1 Replies
4. Shell Programming and Scripting
my intension is to use a grep command inside the shell script
and if any row is returned or not..
depending on the resultset i have to code on further.
how to check this
i mean.. could anyone help me out with the if condition how to use it here !! (4 Replies)
Discussion started by: gotam
4 Replies
5. Shell Programming and Scripting
I have been experiencing this problem intermittantly, I thought the problem was '/bin/sh -> /bin/dash' but I changed that to bash and the problem persists.
I am writing functions to be included in user's '.bash_profile' through source or '.' filename a quick example of the problem is illustrated... (3 Replies)
Discussion started by: bsquared
3 Replies
6. Shell Programming and Scripting
Hello All,
I am running source command on my project configuration file app.cfg which has conditional statements with make file systax E.g ifeq ($(APP_CMP_DIR),trunk).
When I source this file it throws error: syntax error near unexpected token... (1 Reply)
Discussion started by: anand.shah
1 Replies
7. Shell Programming and Scripting
Input is list of Server's, script is basically to remove old_rootvg, So it should check first command "alt_rootvg_op -X old_rootvg" if it passes move to next server and starts check and if it fails moves to other command "exportvg old_rootvg" for only that particular server. I came up with below,... (6 Replies)
Discussion started by: aix_admin_007
6 Replies
8. Shell Programming and Scripting
Hi,
Is there any specific command to use to check only say Running jobs via autorep or similar command for Autosys? (0 Replies)
Discussion started by: sidnow
0 Replies
9. UNIX for Beginners Questions & Answers
Under one of my directories on server I have more than 500 files with different type and name. When I run the find command to list the files with 'ABC_DEFGH' in the begining of its name and older than 20 days, nothing is return as result. Though I know there are more than 400 files which their name... (10 Replies)
Discussion started by: Home
10 Replies
10. Red Hat
Hi there, I'm currently working on an exercise to connect to a Windows iscsi target via a Red Hat initiator machine. I'm using Windows Server 2012 and Red Hat Enterprise Linux v7.1
I have created the target on the Windows Server box and the two devices can communicate with each other. Verified... (3 Replies)
Discussion started by: Tech87
3 Replies
AMIN(1) General Commands Manual AMIN(1)
NAME
amin - notify writers that you are busy
SYNOPSIS
amin [-ynesp] command [args...]
DESCRIPTION
Amin is used when you don't want to be written while running a command. It runs the command given normally. If your message permissions
(see mesg(1)) are off, it does nothing much else. If your messages are on, people writing you with write(1) will be warned that you are
running that command and will be given the opportunity to change their minds about writing you.
The -n option may be used to turn your messages entirely off for the duration of the execution of command. People writing you will get
"Permission denied". The -y option turns your message permissions on for the duration of the execution of the command. The -e may be used
after either -n or -y to indicate that the logins listed in the .yeswrite or the .nowrite files respectively are exceptions to the message
permissions set. The default is -s which leaves your message permissions in their original state. In any case, after the command is com-
plete, your permissions will be restored to the original state.
The -p flag causes all telegrams sent to you while the command is running to be saved. They are displayed as soon as the command is com-
plete. If used with the -n flag, writes are refused, but telegrams are still saved.
If you have designated yourself as a helper, you will still be marked on the finger(1) output as a helper while you are running amin but
people doing ``write help'' will not be connected to you, even if you have the helper flag set to ``Y''.
AUTHOR
Jan Wolter
FILES
/etc/wrttmp to find message permissions
/etc/utmp to find user
SEE ALSO
mesg(1), finger(1), write(1), huh(1).
7th Edition July 1, 1991 AMIN(1)