Hi all,
Forgive me for asking for help with my first post, but I am struggling here. I've been asked to translate a bash script into a Windows script (probably batch or powershell, not sure yet), so the first step is obviously understand what the bash script is doing. But I have no experience in bash, very little in unix/linux, and no unix box to practice on.
I can't figure out the following code:
The first two lines obviously setup variables. Following the exec line, the script continues with various if loops to create folders and copy and zip files. So what is the exec line doing?
From what I read, exec starts a new process, executes the passed parameter and then exits, but in this case there is no passed parameter as far as I can tell, and the script does continue after this line.
A colleague postulated that it is setting the output for the following lines in this script to go to the log file in case of a command returning "1" and to an err file in the case of a command returning "2", or something like that. Can anyone clarify?
If command is supplied, it replaces the shell without creating a new process. If no command is specified, redirections may be used to affect the current shell environment.
If there are no redirection errors, the return status is zero; otherwise the return status is non-zero.
Hope it would help you to understand why they used exec in the script
exec is a shell built-in. While it can be used to replace the current shell process with some other command, it is also used to manipulate file descriptors in the current shell. In this instance, since exec's arguments consist solely of redirections, no command is executed; exec is redirecting standard output, 1>, and standard error, 2>, to two different log files.
To experiment and learn, you can install Cygwin on your windows machine. The default install includes bash and other core utilities.
Ok, so my colleague was more or less right. Any standard output from subsequent commands will go to the log file, and any standard error output from subsequent commands will go to the err file.
If I wanted to cancel this behaviour later in the script, how would I do that? Perhaps:
?
If I wanted to cancel this behaviour later in the script, how would I do that?
Depends what you mean by cancel.
If you simply want to discard output and error messages so that they cease to appear in the logs, you can redirect to /dev/null (although this will not affect any commands that are already logging and running).
If instead you would like to revert output and errors to their original destinations, you'll have to use exec to save the original locations.
Hello.
From a script, a command for a test is use :
find /home/user_install -maxdepth 1 -type f -newer /tmp/000_skel_file_deb ! -newer /tmp/000_skel_file_end -name '.bashrc' -o -name '.profile' -o -name '.gtkrc-2.0' -o -name '.i18n' -o -name '.inputrc'
Tha command... (3 Replies)
I have the following bash script lines in a file named test.sh.
#!/bin/bash
#
# Write Date to cron.log
#
echo "Begin SSI Load $(date +%d%b%y_%T)"
#
# Get the latest rates file for processing.
#
d=$(ls -tr /rms/data/ssi | grep -v "processed" | tail -n 1)
filename=$d
export filename... (3 Replies)
Hi,
I have the following lines in a script :
.
.
exec < some_file
.
.
.
I have very little idea about exec command. I would like to know what this does and what will happen if the file some_file does not exist. Specifically, I would like to know whether the lines following this... (5 Replies)
Hi can some one explain the following command , It would really help if some can really elloborate on what is happening out here
export PATH | exec /bin/sh ./auto_approve :q
P.S: This is the first time i am using exec ,so an elloboration what does it do and what is the use of the :q will be... (1 Reply)
How can I use the exec command to log my korn shell session to the screen and the log file?
Currently I have this command:
$exec 1> ${LOG} 2>&1
This logs the output to the log file only. I want it to go to the screen also. Is this possible with this command?
thanks. (10 Replies)
All,
I am using below shell script to output the content to outputfile.txt. What I am looking for is in addition to outputfile.txt, I want the output to be on standard output too.
exec > outputfile.txt
echo "Starting "
echo "ending" (5 Replies)
I have a ksh script that contains the following:
find /dir1/dir2 -type f -name "FILE.*" -newer /dir1/dir2/afterme.txt -exec cp /dir1/dir2/dir3 {} \;
When I run it from the cli, it runs fine. When I run it from the ksh script I get
find: missing argument to `-exec'
I also tried -exec cp... (40 Replies)
hai
i want know the difference between two shell scripts those are
1)
a=2004
echo $a #output------2004
exec < inputfile
while read line
do
echo $a #output-------2004
a=2005
echo $line
echo $a ... (1 Reply)
linux redhat 8.0
I am getting accustomed to using the -exec command to get around my databse.. and use it to edit and update files..! is this more apllicable than jumping from one directory to the other.. I have set up the databse so that the inode #'s are accessable and can get me from one... (0 Replies)