Programming :: SH: Passing A Variable Out Of A "while - Do - Done" Loop
Jul 3, 2011
"While ; do ; done" is very convenient for SH coding. However sometimes you may be annoyed by your computed variable within the "while do done" type loop. What to do how to pass it out of the loop to the outside of the bash code? A solution is to write it into the /tmp or on the disk... and to call it back after. - not elegant... really not... Anyone would know a trick another alternative that would look nicer?
Code:
# Count file total size
TOTAL_SIZE=0
LISTOFFILES=`cat "$HOME/.fvwmoscfg/fvwmburnerlist.lst"`
echo "$LISTOFFILES" | while read i ; do
SIZE=`du -bs $i | cut -f 1`
TOTAL_SIZE=`expr $SIZE + $TOTAL_SIZE`
echo "$TOTAL_SIZE" > "$HOME/.fvwmoscfg/fvwmburnerlisttotalsize.lst"
done
TOTAL_SIZE=`cat $HOME/.fvwmoscfg/fvwmburnerlisttotalsize.lst`
echo "The total size of all files and folders is : $TOTAL_SIZE"
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Aug 21, 2009
I'm trying to read content of file to variable and use this variable in for loop. The problem is, when I have c++ comment style in file - /*. Spaces in line are also interpreted as separated lines.
For example:
Code:
Changing $files to "$files" eliminate these problems but causes that whole content of variable is treated as one string (one execution of loop).
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May 8, 2010
I have a file with around 1000 IP addresses in it and I need to be able to ssh into each one of them, run a single command, and then exit. I already know the ssh command I want to run and it looks like this:
Code:
shpass -p [password] ssh -p 10022 -o StrictHostKeyChecking=no root@[ip variable] 'reboot'
(I know shpass is not good to use and keys are the correct way but I don't have any other options in this scenario.) if these ip addresses were in a .csv file, by themselves with no other information, how would I create a script to do the above command to each ip until the end of the file?
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Jan 14, 2009
I cannot for the life of me get this little (simple) script I wrote to work. Here is the entire script:
Code:
#!/bin/bash
ASPECT=`mediainfo $1 |grep "Display aspect ratio" |cut -d : -f 2`
HEIGHT=`echo "320 / $ASPECT" |bc`
SIZE=`echo 320x$HEIGHT`
[code]......
An input filename ($1) is fed into mediainfo, which by the use of grep and cut spits out a single number which is the aspect ratio. This is then divided by bc into 320, which gives the desired height dimension for the file that I want ffmpeg to create for me. Finally, ffmpeg runs using the calculated dimensions... Basically, it's the passing of the $ASPECT variable to bc that seems to fail. It looks like bc won't read the output from the mediainfo line... It always crashes out with:
Code:
(standard_in) 1: illegal character: ^M I've tried doing something even simpler like this to debug by just trying it to display the calculation on the screen:
Code:
#!/bin/bash
ASPECT=`mediainfo $1 |grep "Display aspect ratio" |cut -d : -f 2`
HEIGHT=`echo "320 / $ASPECT" |bc`
echo $HEIGHT
and it does the same, so it's definitely bc that won't accept the output from mediainfo.
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Jan 9, 2014
I want to build on the code from /etc/apt/apt.conf.d/05etckeeper to work with Snapper, the new-in btrfs (et al) snapshot package.
Code: Select allDPkg::Pre-Invoke    { "if [ -x /usr/bin/etckeeper ]; then etckeeper pre-install; fi"; };
DPkg::Post-Invoke   { "if [ -x /usr/bin/etckeeper ]; then etckeeper post-install; fi"; };
The etckeeper code will work well as a template, but I need to pass a parameter between the pre- and post- instances. The parameter is obtained from the pre- invocation and passed to the post- invocation.I know that something similar to my quest is done with the 'pid' but how to do it in the 'standard' way. Happily there can't be multiple dpkg instances running concurrently (prevented by dpkg?) so I don't have to worry about that issue.
Q1. What is the 'standard' way of passing parameters about?
Code: Select allsnapper -c etc create -t pre -p   (which 'prints' the parameter (int) to pass to the following invocation)
snapper -c etc create -t post --pre-number <parameter> in place of the two etckeeper calls.
Q2. How do I pick up the 'printed' output of the 'pre' call? I think it's just a 'get' from the stream but perhaps I've missed something.?
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Apr 12, 2010
I want to know is there some more efficient way of passing a pointer to a local variable as a parameter to a function in x86 asm? Right now I have to move the base pointer to a temp register, subtract from the register and pass that, like this (assuming a local var at esp-4):
Code:
mov eax, ebp
sub eax, 4
push eax
Is there a better way?
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Jul 11, 2011
I'm having some trouble this morning to send a SQL query to our Oracle DB server in PHP. When I try to pass my value "OF/110246801A01" as variable it tell's me "Warning: oci_bind_by_name(): ORA-01036: illegal variable name/number"
PHP Code:
$ociO ='OF/110246801A01';
$selectAllFieldsFromOf=oci_parse($conn,"SELECT*FROMMFGOPEWHEREMFGNUM_0LIKE':ociOf' ");
oci_bind_by_name($selectAllFieldsFromOf,":ociOf",$ociOf,15);
$resultQuery =oci_execute($selectAllFieldsFromOf);
if(!$resultQuery){
$e = oci_error($selectAllFieldsFromOf);
return trigger_error(htmlentities($e['message'],ENT_QUOTES),E_USER_ERROR);
[Code]....
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Jan 21, 2011
Say, i have an imaginary std library function, which I want to call.
Code:
void std_lib_func(ObjectType *param);
Now in my c++ program, I have a main() function, and I will like to call a customized function (which will in turn call the std lib function) from the main function, as below:
Code:
int main()
{
ObjectType *aobj;
customized_func(aobj);
}
[Code]...
I tried the below but get an error that the std lib function is expecting a ObjectType* param, not aobj. How should I work this out.
Code:
void customized_func(ObjectType aobj)
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Aug 27, 2010
How can I to pass a perl variable into html input tag? For example, If a have got a cgi script:
Quote:
use CGI;
use DBI;
my $owner = $cgi->param('owner');
[code]....
How can I to pass $owner variable?
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Sep 17, 2009
I'm trying to implement an assert function similar to:[url]
However, I'm having trouble with file existence testing when the file name has a space in it.
I have distilled the problem down to the following:
This code works as expected, printing 'yes' if '~/test file' exists, and no if not.
Code:
However, this code gives an error.
Code:
The error:
Code:
Which tells me that it is splitting ["~/test file"] into ["~/test] and [file"]. Why? Is there a way around this?
Note that if you simply use a file path without a space, both cases work perfectly. Is this a BASH bug possibly? I just can't understand why the first would work, but the second wouldn't.
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Mar 25, 2011
I have a directory file capturing script, the variable is fine with in the loop but gone after the loop is done:
Code:
DIR="/usb/sdb1/media/music/"
i=1
[code]...
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Jan 14, 2010
I want pass a variable at compile time.
for example in x.c
int global_var = POSITION;
How can I send this POSITION at compile time. ie like # make POSITION=10 Is it possible?
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Apr 24, 2010
I am about to move my scripts to the next generation level, so I need some help I am stuck in varying my variable names in a loop. For example:
for user in ben dorothy mike pat
do
[ -r /home/$user ] && let "$user"check=1 || let "$user"check=0
[code]...
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Jul 3, 2009
I know of 4 different ways to use a for loop:
1. for I in {1..10}; do echo $I; done|
2. for I in 1 2 3 4 5 6 7 8 9 10; do echo $I; done|
3. for I in $(seq 1 10); do echo $I; done|
4. for ((I=1; I <= 10 ; I++)); do echo $I; done
I have a script which uses the 1st form of for loop. I'm trying to modify it to use a variable instead of a static hard-coded value in the section that controls the looping.of the for loop.
I've tried all different ways of quoting and escaping the variable, and the problem is that the quoting chars and escape char are being translated and passed into the loop along with the value stored in the variable.
For example, to change the start value of 1 to whatever value I want passed in through a variable:
Change:
I have tried: {{$a}..10} and {`$a`..10}, to have the variable evaluated first.
I have tried using the eval() function.
I have tried single and double quotes and the backslash escape character.
Nothing I've tried works. It's probably a syntax error.
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Oct 14, 2010
I have a bash variable where the content looks like this where ;f1; and ;f2; are delimiters:
;f1;field1value1;f2;field2 value1 ;f1;field1value2;f2;field2 value2 ;f1;field1value3;f2;field2 value3
So what I need is to extract and put into variables each combination of f1 and f2 in a loop to something like that:
#first pass of the loop I need:
f1=field1value1
f2=field2 value1
#second pass of the loop I need:
f1=field1value2
f2=field2 value2
# third pass of the loop I need:
f1=field1value3
f2=field2 value3
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Jul 22, 2011
I'm reading "OReilly Learning Perl 5th Edition", and there are such words:Code:You can use an array element like $fred[2] in every place? where you could use any other scalavariable like $fred.At the bottom of the page, it explains the ? like this:Code:The most notable exception is that the control variable of a foreach loop, which you?ll see later in this chapter, must be a simple scalar.Since Perl has the save-and-restore mechanism for the control variable, why an array element can't be used as the control variable
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Mar 17, 2011
I'm trying to do substitutions to a file based on passed variables.
For example, I have a file called test.txt that has 5 lines:
What I want to do is to go through that file, line by line and check for the presence of a passed variable in that line. If I have a match, then substitute and print, otherwise print line as is. My problem arises in that the number of variables is well, variable.
The code I started with was the following:
Code:
What I was hoping for was test.out to look like this:
What I get is a much longer file like this:
This makes sense after thinking about it but is there anyway to get an output like the first case?
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Jan 8, 2011
I am new to bash scripting. I want to know whether i can pass one variable to another. For example $1 represent argument1. Now if i want to get the argument 1 like USER="1" now i want $ of $USER to execute $1 so what should i do..
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Jul 24, 2010
How can I pass xml data from memory or a variable to xmllint that expects a file as input? Or does xmllint have the capabilities to read from stin or a variable?
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Jun 19, 2010
I have installed FC13 on my laptop and set it up as a development server. Here is my issue when passing variable from one page to the next it gets lost. My PHP includes work DB connect string works from the include.
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Jan 27, 2011
I really don't get this!! I must be doing something really foolish but i can't figure out what it is.
Code:
#!/bin/bash
pro_num=0
[code]...
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Feb 11, 2010
I am trying to write a script that will find any user on the server running more than one instance of the epiphany web browser process, then kill all their epiphany pids. (This is necessary sometimes to cure lockups, and repeat processes are the telltale sign in this case). I have tried implementing the until loop:
Code:
USER=`ps aux | grep epiphany | grep -v grep | sort | uniq -d -w 5 | awk '{print $1}'`
until [[ "$USER" == "" ]]
do
ps aux | grep epiphany | grep -v grep | grep $USER | awk '{print $2}' | sudo xargs kill
done
Unfortunately, the script only calculates the USER variable once at the beginning of the script. Fair enough, that's how it's written. My question is, how would I get the USER variable to update for each pass of the until loop so that it could cure multiple users of this ailment if necessary? That is, calculate $USER, kill their epiphany pids, repeat those two steps until the $USER variable comes up blank, then exit.
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Mar 1, 2011
As you can see on the output of the script, the two 'testing echoes' I do at the end don't print anything.That's the point, I do NEED this array further in my script.I'd understand my "param" var is local to the for, but is the other one too ? I tried to use "declare -a file" before the for, but i get same exact result !
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Jan 19, 2011
I modified files in several directories, and need to run a diff on the backup I created before modifying the file.
I'm trying to compose a simple shell script to speed up the task, but getting a syntax error.
Here is what I have:
for i in DIR1 DIR2 DIR3 DIR4 DIR5 do;
diff /maindir/subdir/subdir/$i/filename.txt.old /maindir/subdir/subdir/$i/filename.txt;
done
I know the paths are valid, and if I run just the diff command with the actual DIR1 instead of $i it works.
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Apr 7, 2010
my script has a variable which comes in the form +00.00 +0.00 -00.00 or -0.00 (the numbers can be any in that form) for any that have a + symbol I need to remove the +, but if it has a - symbol it needs to stay.
i need to make a new variable with the string from the old variable btut without any plus sign. I have tried a lot of different ways with no success, each thing I tried either left the + or removed the entire string. I think this should work but doesn't
foo=+12.40
bar=${foo#+}
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Mar 9, 2011
I am trying to make a simple alias for find command that acceps a variable.
alias myfind="find $@ -type d -exec chmod 777 -fv {} ;"
this alias tells me that "find:paths must precede expression"
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Apr 25, 2011
how I can search within a variable and assign the results to a new variable. I'll use the following as an example -
cars="Audi BMW Cadillac Chevy Dodge Ferrari Ford Mercedes"
list=`echo ${cars} | egrep -o '<A?+|<C+'`
with the echo command I get the following output assigned to list -
A
C
C
What I'd like to get for output is -
Audi
Cadillac
Chevy
how I could do this regardless of upper/lower case letters?
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Apr 28, 2010
included shell script inside c program, and i wanted to assign the value of c variable to shell variable..Can any one please suggest me how to do it?
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Feb 8, 2010
i have written a script in which, i changes a variable using a "while" loop. then i feed that variable to an input file. After that i run that file in parallal using mpi library.Script is as:>>>>
#!/bin/bash
STA=/home/sk/Desktop/exefile
sta=mpirun -np 6 $STA
[code]....
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Mar 17, 2011
This loop is part of a bash script which takes multiple arguments.
Code:
for ((i=1;i<=$number;++i)) ; do
offset=$(($i+5))
[code]...
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