$ ls
abc.dat
$ ls abc.dat > /dev/null 2>&1
$ echo $?
0
$ ls 123.dat > /dev/null 2>&1
$ echo $?
1
$
---------- Post updated at 11:40 ---------- Previous update was at 11:35 ----------
Quote:
Originally Posted by angshuman_ag
Some tools are returning long strings. So suppose I want to grep on a string like this -
Code:
"Status: XXXX"
where XXXX denotes number. How do I do that ? And, if that particular string is matched, I would want to do some operation.
We would need the complete output of that particular command, than we could offer you an appropriate awk or cut command, which will e.g. use ":" as field delimiter character
Dear Experts,
I put below command-
could you please describe the outputs column-
let me describe some them-
col_1: (10.131.60.48.55880) The IP address of the local computer and the port number being used for this particular connection appear in the Local Address column.
col_2:... (3 Replies)
Suppose I have a file named a
When I write
cat a>a
The following error message is displayed
cat: a: input file is output file
and my file a is truncated to zero size.
Also the exit status of the last command is 1
Can someone tell me what actually happens when I do so? (1 Reply)
Hello bash experts.,
I was doing some experimentations to better understand the following redirection.,
$Output = `sh -c \"$Cmd 2>&1 1>&2\"`;
It is actually the line used in one of the perl program, but the technique i am trying to understand is related to shell scripting.
So is there... (5 Replies)
I'm redirecting the output of a command to a logfile, however, if the user is on a terminal I would also like the output to be displayed on the screen.
tar tvf some_tarfile >Logfile
if the user is on a term then have the output to the Logfile and also be displayed on the screen at the same... (2 Replies)
Hi there
I have a script that runs but it outputs everything onto the screen instead of a file.
I've tried using the > outputfile.txt however all it does is dump the output to the screen and creates an outputfile.txt but doesn't put anything in that file.
Any help would be appreciated
... (6 Replies)
We have an application here that does some table queries and then prints the result on screen. I do not have the code of this application (which i will just call "queryCommand"), but what it does is that you call it with some parameters and it prints some info about the query and then the... (5 Replies)
Hello i am trying to write a script that will redirect the output to a certain file. Here is the code so far:
#!/bin/bash
ps -e | sort | more > psfile
When I execute the script nothing happens since i assume the output was redirected to the file called psfile. When I try to look at the... (1 Reply)
Hi
I am making a script where i want to redirect the output of ls -l to a file
Example
#ls -l fil1.txt > /opt/temp/a.txt
ac: No such file or directory
I want to capture output of this command
like here output is
ac: No such file or directory
can anyone help (4 Replies)
Hi all
I was wondering if there was a slicker way of doing this without the file -
awk '{print $2}' FS=":" "${FILE}" > "${TMPFILE}"
{
read M_GRP_ID || m_fail 1 "Error: Read failed 1 (${FUNCNAME})"
read M_GRP_WAIT || m_fail 1 "Error: Read failed 2 (${FUNCNAME})"
}... (6 Replies)
Hi All,
i have below for loop of which i am trying to redirect output in a file:
for i in `/usr/sbin/ifconfig -a | awk '/flags/ {print $1}' | grep -v lo | sed 's/://g'`
do
ifconfig $i dhcp status
done >> /tmp/logfile
but instead the output is appearing as stdout on screen rather than... (12 Replies)
Discussion started by: omkar.jadhav
12 Replies
LEARN ABOUT CENTOS
shell-quote
SHELL-QUOTE(1) User Contributed Perl Documentation SHELL-QUOTE(1)NAME
shell-quote - quote arguments for safe use, unmodified in a shell command
SYNOPSIS
shell-quote [switch]... arg...
DESCRIPTION
shell-quote lets you pass arbitrary strings through the shell so that they won't be changed by the shell. This lets you process commands
or files with embedded white space or shell globbing characters safely. Here are a few examples.
EXAMPLES
ssh preserving args
When running a remote command with ssh, ssh doesn't preserve the separate arguments it receives. It just joins them with spaces and
passes them to "$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)
05-18-2010
