Programming :: Bash Script: Assign Command Ouput To A Variable Without Executing It?
Feb 12, 2011I'm trying to execute the following command within a bash script:
Code:
tac /var/log/system.log | head -1
The script I wrote is:
[code]...
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Debian Programming :: Assign Variable In Bash When Stdout Is Updated
Jan 17, 2014I am writing a script that calls a program which writes a lot of lines to stdout continuosly. If the last line in stdout has some regex, THEN, certain variables are updated. My problem is that I don't know how to do that.
A simplified example would be (it's not my exact case, but it I write it here to clarify): suppose I issue a ping command (which writes output to stdout continuously). Every time that the response time is t=0.025 ms, THEN, VARIABLE1=(column1 of that line) and VARIABLE2=(column2 of that line).
I think the following code would work in awk (however, I want the variables in bash and I don't know how to export them)
Code: Select allping localhost |awk '{ if ( $8 == "time=0.025" ) var1=$1 var2=$2}'
In the previous code, awk analyzes each line of the output of the ping command as soon as it is created, so the variables $var1, $var2, ... are updated at the appropriate time. But I need the "real-time" updated values of $var1, $var2 in bash, for later use in the script.
Programming :: Bash Scripting...read A Value From A File Then Assign To Variable?
Feb 27, 2011At my wit's end I can't find anything that I understand well enough to use. This is for a Unix class, we are working with shell scripting. File1 has 5 in it and File2 has 100 in it.The teacher wants us to read the values then do the math. This is what I have so far:#!/bin/bashvar1='cat File1'var2='cat File2'var3=`echo "scale=4; $var1 / $var2" | bc`echo The final result is: $var3
View 9 Replies View RelatedProgramming :: Search Within A Variable And Assign The Results To A New Variable?
Apr 25, 2011how 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?
Programming :: Assigning Bash Variable With The System Command In Awk?
Mar 1, 2011I am having all sorts of trouble trying to assign a variable within an awk script with the system command. I know there is a lot of ways around this problem, but for efficiency reasons, I would like to, within my awk script, do something like
system(x=3)
or
system(x=NR)
and, latter on the shell script which calls the awk script, use the variable $x. But nothing is passed to x. I have already tried things like
command = "x=3"
system(command)
and also used a pipeline within the system to pipe it to /bin/sh In fact tried a lot of stuff like that, using $(( )) etc etc etc I can create directories e write to files (yes, i could write to a file and read from there, but I dont think it is efficient, plus I am puzzled).
Programming :: Assign Value Of C Variable To Shell Variable?
Apr 28, 2010included shell script inside c program, and i wanted to assign the value of c variable to shell variable..Can any one please suggest me how to do it?
View 8 Replies View RelatedRed Hat / Fedora :: Assign A Variable To A Command?
Sep 10, 2010I can print a specific line of a file with:$ sed -n '20p' myFileHow can I store it in a variable (in a shell script)?(I wasn't successful with "myVar=sed -n '20p' myFile" for example)
View 2 Replies View RelatedProgramming :: Bash - Read Content Of File To Variable And Use This Variable In For Loop ?
Aug 21, 2009I'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).
General :: Assign An "here Documents" Section To A Variable In Bash?
Mar 11, 2011Is it possible to assign an "here documents" section to a variable in bash?I would like to assign the following to a variable:
Code:
<html>
<body>
<p>THis is a test</p>
</body>
</html>
Programming :: Reading A Bash Variable In Bash Scripting ?
Nov 26, 2008I have a config file that contains:
my.config:
Code:
Now in my bash script, I want to get the output /home/user instead of $HOME once read. So far, I have managed to get the $HOME variable but I can't get it to echo the variable. All I get is the output $HOME.
Here is my parse_cmd script:
Code:
General :: Assign Local Variable Values To Global Variable?
Feb 17, 2011how to assign a local variable value to a global variable....
View 2 Replies View RelatedProgramming :: Check If The User Is In Correct Directory Before Executing Bash Script
Dec 10, 2010I have been searching for 90 minutes for something that I "think" should be fairly easy. I'm pretty new to Bash Scripting so I could be completely wrong. Then again it may be a weird request to even need something like this. But here it is.I have a script written to convert data from one of our software version to another. The only thing I need to add to it is a "check to make sure the user running the script is in the /tmp directory".
View 7 Replies View RelatedProgramming :: Executing Shell Command In JSP
Aug 24, 2010what we are trying to do is, to let the customer click a button in the web browser, and then the web server to call a shell script to do the work. The output from the stdout && stderr of the script should be displayed in the web browser once finished or timeout, along with the exit code of the script.
The shell script is however not on the web server, but on another app server. So to call this script from the web server as the identity 'tomcat':
Code:
$ sh appuser@app-server:$appbin/app-script
The .ssh/id_rsa.pub thing is done, and we have no problem doing this in the command line so far.
Our loaded ex-colleage has left us the webpages (jsp) with code like these:
Code:
<%@ include file="jsp_functions.jsp" %>
<%
String cmd = "sh $appbin/app-script";
ExecResult r = new ExecResult();
[Code].....
General :: Simple Bash Command Causing Bad Variable Name
Feb 18, 2010When I run this command from shell, it runs ok
export REVS=`svn info svn+ssh://svn.myone.ca/var/svn/story/trunk/lib |grep 'Last Changed Rev:'| awk -F: '{print $2}'`
However when I save it into a file called test.sh (of course, I chmod it with +x), I got error "export: 2: bad variable name"
Here is the file:
#!/bin/bash
export REVS=`svn info svn+ssh://svn.myone.ca/var/svn/story/trunk/lib |grep 'Last Changed Rev:'| awk -F: '{print $2}'`
I am using ubuntu.
General :: Environmental Variable In Bash Command String?
Feb 9, 2011I do this:
Code:
a@b:~$ export A=hi
a@b:~$ echo $A
hi
a@b:~$ bash -c "export A=blah; echo $A"
hi
a@b:~$
Why doesn't the bash command print the new value of $A? Is there a way to make it do so?
Programming :: Sed A Variable In Bash?
Mar 25, 2011I have beat this enough and don't get what should have been a very simple thing to do. I build a variable;
Code:
CLIST=java,lua,python,php,perl,ruby,tcl
CLIST will be used by another bash script but I need to replace the commas with a space. I
[code]...
Programming :: Executing An External Command With Python (CGI)
Jul 8, 2011I need to execute an external command with Python from Web. I know there is subprocess module that executes external programs but I'm trying to execute a command registered for the execution of a program. In this case when I execute my file in the shell everything is Ok, but from the Web it doesn't work.
View 1 Replies View RelatedProgramming :: Variable Substitution In BASH?
Feb 17, 2011Just a simple BASH for loop to read the file path from a text file (clean.txt) echo the variable for debug purposes, and scp it to a server I have using port 50 for SSH.
I've already formatted the entries in clean.txt to handle spaces correctly, using sed replacement.
Example from the clean.txt file:
Code:
/MP3/NAS000000001/Barenaked Ladies/Barenaked Ladies - Barenaked For The Holidays/20 Auld Lang Syne.mp3
/MP3/NAS000000001/Barenaked Ladies/Barenaked Ladies - Barenaked For The Holidays/14 Deck the Stills.mp3
[Code]....
Programming :: How To Use Bash Variable In C Code?
Feb 16, 2011I want to write a c program with some shell scripts.Now For a simple C program. I am Setting a variable called val2 in bash, now I want to use bash variable val2 in C code. How do I do that?The above doesn't work (coz its spawning a different memory space and when shell script ends the variable dies with it as per my research but how do I keep them in same memory space)Also Is there any Good reference where they teach how to integrate C and Bash Together?
View 5 Replies View RelatedProgramming :: (BASH) Keep Variable In Scope?
Jul 15, 2011i've just started to learn about functions in Bash scripting. I'm able to set the functions and execute the commands correctly. However, if my_var is set in the first function and then later in the script in the script the 2nd function is called, it doesn't seem to remember my_var and quits (at least i suspect this is the problem).
Here's my code (it requires yad available via webupd8. org). My specific problem seems to lay in line #27 where if we view the changelog and then exit that window, it returns to the "main" function but any subsequent commands cause a crash. Is this because of the get command on line #29? It's presumably now out of scope after calling menu on line #25?
Programming :: Bash - Passing Variable To Ssh?
May 8, 2010I 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?
Programming :: Passing A Variable To Bc In Bash ?
Jan 14, 2009I 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 $HEIGHT
and it does the same, so it's definitely bc that won't accept the output from mediainfo.
Programming :: Setting Variable In Bash With Sed?
Jun 18, 2011I am killing myself with this, please someone come to the rescue...
Code:
#!/bin/sh
IFILE=$@
[code]...
Programming :: Bash Concatenating String To Variable ?
Jan 18, 2011I have a program that loops over each word in a sentence. I need to append a constant to the beginning and end of each word. It works up until the last word on the line.
Code:
Output:
Programming :: Bash: Give A Variable The Value Of A Function?
Aug 8, 2010I was wondering if possible in bash for a variable to take the value of a function, I mean the function returns a value and a variable will take it. example:
[Code]....
Programming :: BASH - If Variable -eq String Not Working ?
Jan 24, 2010Here is the code:
Code:
How ever when I run this script I get the following error
Quote:
I just don't get it, I have racked my brain trying to figure out every combination of how I should write this if statement and I can't get it to work.
Programming :: Bash: Making A Variable Out Of Two Other Variables?
Mar 18, 2010I need to find the value of:
Code:
$Namenumber
My script asks for the name you want to look up and I want it to return the value of $Namenumber
I was thinking:
Code:
number=$"$name"number
but this returns
Code:
$Namenumber
but does not actually resolve what the variable $Namenumber is equal to.
Programming :: Bash - To Prepend Text To Variable
Feb 13, 2010The output of following code is not like it's intended ...
Code:
This is the output:
Code:
Test prepending ...apple is a nice word, hour is a nice word, But of course what I want to do in the first set of commands is to prepend the word "an" to the words "apple" and "hour" in the for-loop.
Programming :: Bash Redirection With Exec: Specify Fd With Variable?
Feb 21, 2010Within a bash script, I'm attempting to redirect file descriptors with exec, e.g. exec 3>&1 1>&2; however, I'd like to do something like exec $FD>&1 1>&2, which doesn't work because bash tries to execute the value of $FD. Various placements of eval fail, as well. Is there a way around this, or am I stuck hard-coding the descriptor?
View 3 Replies View RelatedProgramming :: Grep For Variable In A Bash Script?
Aug 19, 2010I've tried every combination of ' " that I have come across in similar threads on the forum but no luck.. I have 2 files
strings.txt: contains a list of numbers, 4 digits per line file.
txt: contains a lines that I want to grep for the strings.
for example:
>cat strings.txt
3214
8746
2411
[code]....
if I echo $i in the loop, I print out the contents of strings.txt If I put 3214 in place of grep "<$i>" file.txt I get "carls phone number is 3214"