Hi all,
I'm trying to write a program that has some data it wants to send through a filter program(in this case tr), and then recieve the output from that filter program. The way I'm trying to do it is by setting up two pipes between the programs and piping the data in through one pipe and back... (2 Replies)
Hello All,
I have a list of short programs (over 200) to run and it is a hassle to sit and execute each one of them one after the other.
What I'd like to know is if it was possible to create one file which would list all these commands and all I need to do is to execute this one single file.... (2 Replies)
Hi,
I am thinking about writing a log daemon for a multi-processed ksh application (yes - I know that high-level language would be a better option).
My question is as follows:
If many processes (many scripts) will try writing to a single log file:
print "message" > common.log
Will it work or... (2 Replies)
Hi,
I have a file 'imei_01.txt' having the following contents:
$ cat imei_01.txt
a123456
bbr22135
yet223
where I want to check whether the expression 'first single alphabet followed by 6 digits' is present in the file (here it is the first record 'a123456')
I am using the following... (5 Replies)
Hello,
I would like to pipe two variables into awk, but I don't know how to do.
Each variable, "a" and "b", are in fact a list of data. They are not files.
So to get awk to work with it I am using:
echo $a | awk 'FNR==NR{print $1}FNR!=NR{print $4}'
The above works, but when I am... (5 Replies)
I'm writing a PHP script which will take a given media file and convert it into a flash (flv) file. In addition to this, once the flv file has been generated I create two thumbnails (of different sizes) from the newly generated flv file.
In order to do this I'm calling ffmpeg from the command... (4 Replies)
Hey all, I need a command line that creates a new file named whatever, say stuff.txt in the current working directory which contains the number of directories in the current working directory, followed by the number of empty files in the current working directory, followed by the name of the... (2 Replies)
Hi guys, I'm having some problem here, I'm studying pipes, and i want to create a shell in C and at this point a don't want to use semaphores, instead I want to use tricks. Straight to the doubt: I've a parent and a child process, and both of them has some code to execute, and the child process... (5 Replies)
Discussion started by: pharaoh
5 Replies
LEARN ABOUT DEBIAN
shell-quote
SHELL-QUOTE(1p) User Contributed Perl Documentation SHELL-QUOTE(1p)NAME
shell-quote - quote arguments for safe use, unmodified in a shell command
SYNOPSIS
shell-quote [switch]... arg...
DESCRIPTION
shell-quote lets you pass arbitrary strings through the shell so that they won't be changed by the shell. This lets you process commands
or files with embedded white space or shell globbing characters safely. Here are a few examples.
EXAMPLES
ssh preserving args
When running a remote command with ssh, ssh doesn't preserve the separate arguments it receives. It just joins them with spaces and
passes them to "$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 v5.8.4 2005-05-03 SHELL-QUOTE(1p)