Friends,
I did following exercise
$ echo '' > test
$ od -b test
$ echo "">test
$ od -b test
$echo > test
$od -b test
Every time I got the following output
0000000 012
0000001
But 012 is octal value for new line character .
Even though there is no apperent new line character... (6 Replies)
Hello. I'm a complete newbie to C programming. I have a C program that wasn't written by me where I need to write some wrappers around it to automate and make it easier for a client to use. The problem is that the program accepts standard input to control the program... I'm hoping to find a simple... (6 Replies)
Hi Guys,
I've been learning UNIX for the past couple of days and I came across this exercise, I can't get my head around it, so I would be ever so grateful if I could receive some sort of help or direction with this.
Create a file with x amount of lines in it, the content of your choice. ... (3 Replies)
Hi,
Please don't berate me over the simplicity of these questions. I have recently gotten into bash shell scripting and enjoy it quite a bit. One thing I have not found the answer to though is when naming a shell script, what extension is normally used (ie myscript.?)? Also where is the standard... (5 Replies)
I had a script in solaris wich i read data, for example:
Number 1: _
and the cursor use to be in '_' place because in the code of the script i write:
echo "Number 1:\c"
but i copy the script to a linux and the cursor 'jump' to the begining of the next line like:
Number 1:... (2 Replies)
hi everybody;
trying to c unix programming and ive stucked with a problem:
simple program
filedr=open("tempfile",O_RDWR|O_TRUNC,0);
write(filedr,msg1,6);
int i;
i=read(filedr,msg3,4);
it returns 0 bytes read ... why?
well if i try to poll() before read , it doesnt indicate POLLHUP or... (4 Replies)
I am having trouble making this statement work. I am passing in a number value for the number of days to keep archive logs for and wanted to make sure that it is a number. I have a script that will return 1 for is a number and 0 for is not a number. I also want to make sure that the number is not... (2 Replies)
Cheers!
In /etc/syslog.conf, if an error type is not specified, is it logged anywhere (most preferable is it logged to /var/log/messages) or not?
To be more precise I am interested in error and critical level messages. At default these errors are not specified in syslog.conf, and I need to... (6 Replies)
Discussion started by: dr1zzt3r
6 Replies
LEARN ABOUT CENTOS
shell-quote
SHELL-QUOTE(1) User Contributed Perl Documentation SHELL-QUOTE(1)NAME
shell-quote - quote arguments for safe use, unmodified in a shell command
SYNOPSIS
shell-quote [switch]... arg...
DESCRIPTION
shell-quote lets you pass arbitrary strings through the shell so that they won't be changed by the shell. This lets you process commands
or files with embedded white space or shell globbing characters safely. Here are a few examples.
EXAMPLES
ssh preserving args
When running a remote command with ssh, ssh doesn't preserve the separate arguments it receives. It just joins them with spaces and
passes them to "$SHELL -c". This doesn't work as intended:
ssh host touch 'hi there' # fails
It creates 2 files, hi and there. Instead, do this:
cmd=`shell-quote touch 'hi there'`
ssh host "$cmd"
This gives you just 1 file, hi there.
process find output
It's not ordinarily possible to process an arbitrary list of files output by find with a shell script. Anything you put in $IFS to
split up the output could legitimately be in a file's name. Here's how you can do it using shell-quote:
eval set -- `find -type f -print0 | xargs -0 shell-quote --`
debug shell scripts
shell-quote is better than echo for debugging shell scripts.
debug() {
[ -z "$debug" ] || shell-quote "debug:" "$@"
}
With echo you can't tell the difference between "debug 'foo bar'" and "debug foo bar", but with shell-quote you can.
save a command for later
shell-quote can be used to build up a shell command to run later. Say you want the user to be able to give you switches for a command
you're going to run. If you don't want the switches to be re-evaluated by the shell (which is usually a good idea, else there are
things the user can't pass through), you can do something like this:
user_switches=
while [ $# != 0 ]
do
case x$1 in
x--pass-through)
[ $# -gt 1 ] || die "need an argument for $1"
user_switches="$user_switches "`shell-quote -- "$2"`
shift;;
# process other switches
esac
shift
done
# later
eval "shell-quote some-command $user_switches my args"
OPTIONS --debug
Turn debugging on.
--help
Show the usage message and die.
--version
Show the version number and exit.
AVAILABILITY
The code is licensed under the GNU GPL. Check http://www.argon.org/~roderick/ or CPAN for updated versions.
AUTHOR
Roderick Schertler <roderick@argon.org>
perl v5.16.3 2010-06-11 SHELL-QUOTE(1)