Programming :: Bash - Read Content Of File To Variable And Use This Variable In For Loop ?
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).
At 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
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.
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
I googled and tried to find an easy step by step-by-step guide on how to use a bash script read a variable from a file. This is the way I did it (but it does not really work so something is wrong, but what?) (testfil2 contains one line that readsidnumber=1578
instead of importing a file I would like to use the variable $x I tried using pipes, but with no luck. My goal is to read one line at a time, but not have to export my data to another file, I would like to keep it all within one script.
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 !
I am trying to think of a logic where my file contains some data I had to read and do some processing. Issue is that file contains data multiple times. For example:
::::::::::: var1=value1 var2=value2
[code].....
I have to read first paragraph of variables and do some processing and then move on until the end of file. Variable names are same in whole file but for each paragraph the value is different. I can't think of a logic to attain this task. How can I do it? It should be a simple bash script, but I am not able to work out.
I have a problem when i ried run this command (export HISTTIMEFORMAT="%F %T ") on slackware 13.0. the answer is the following (-bash: HISTTIMEFORMAT: readonly variable) I am running this command on the bash like root.
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
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
On one of my servers I see this when I log in. What does this mean and how can I get it to go away? Everything seems to work fine, but none of my other machines give this error.
I am trying to write a script which can read the names of all folders within a given folder into separate variables. In effect, if a folder contains a folder "Folder1", "Folder2", "Folder3", the script would read those names into variables such as:
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 $HOME.
What's the best way to read a value from a configuration file into a script?I'm trying to get the command_file vaule from nagios.cfg into a script, this works but what's the best way to do it?
Code:
command_file=$(perl -F= -lane 'print $F[1] if /^[[:space:]]*command_file[[:space:]]*=/' /etc/nagios/nagios.cfg)
Just 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
I 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?
i'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?
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:
(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?
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:
I 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.