I am a beginner and I have been searching the web all morning for this answer but can't find it anywhere.
I know that
prtint 1*2
will return
1*2
what if i actually want the problem to be calculated
so i want
print 1*2
to return
2
How is this done? (3 Replies)
I am using egrep to extract numbers from a file and storing them as variables in a script. But I am not able to do any arithmetic operations on the variables using "expr" because it stores them as char and not integers. Here is my code and the error I get. Any help will be appreciated.
#!/bin/sh... (3 Replies)
Hello,
I would like to understand this... I'm using ksh and doing
(( z = y - 1 ))
if y=34, then the result for z is 33, but if y=034 the result is z=27. Why??
Thanks (15 Replies)
Hi all,
I´ve already searched the forum but can´t find what i am doing wrong.
I am trying to compare two variables using ksh under red hat. The error I get is:
-ksh: .: MDA=`md5sum /tmp/ftp_dir_after_transfer | cut -d' ' -f1 `
MDB=`md5sum /tmp/ftp_dir_before_transfer | cut -d' ' -f1 `... (3 Replies)
Hello all,
I'd like to know how to perform arithmetic on multiple files. I have got many tab-delimited files. Each file contains about 2000 rows and 2000 columns.
What I want to do is to to sum the values in each row & column in every file.
The following explains what I want to do;
... (9 Replies)
I have a fundamental question on C pointer arithmetry..
Suppose i have a c string pointer already pointing to a valid location, Can I just do a
charptr = charptr +1;
to get to the next location, irregardless if my program is 32 or 64 bits?
or should i do it this way:
charptr =... (1 Reply)
Hello,
I am having a problem when i execute following script on RHEL 6.4. Same script works fine on another machine where I have same version of RHEL and KSH.
Below is the rpm and RHEL version.
ossvm12(0)> rpm -qa | grep ksh
ksh-20100621-19.el6.x86_64
ossvm12(0)> cat... (7 Replies)
Hello fellow forum members,
I wrote below piece of code to calculate the date after a given date -
date=$DATE_FINAL
declare -a max_month=(0 31 28 31 30 31 30 31 31 30 31 30 31)
eval $(echo $date|sed 's!\(....\)\(..\)\(..\)!year=\1;month=\2;day=\3!')
(( year4=year%4 ))
(( year100=year%100... (9 Replies)
I need to divide the number of white spaces by total number of characters in a file using bash. I am able to get the number of white spaces correctly using:
tr -cd “”¯ < afile | wc -c
I am also able to get the total number of characters using:
wc -c afile
How do I divide the first... (2 Replies)
Discussion started by: ngabrani
2 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)