The variable tag has no usage guidance.
0
votes
1answer
18 views
How do you handle multiple validation rules on varied user input?
I'm using a Bash script to prompt users for several variables before continuing. If I want to create static validation rules and execute them on user inputs in an "a la carte" fashion, how would I go ...
1
vote
1answer
31 views
how to get or reflect the name of the bash function which is called? [duplicate]
i did not yet found a solution to this. Anyone a hint?
i sometimes write bash functions in my shell scripts and i love to have my scripts being verbose, not just for debugging. so sometimes i would ...
1
vote
2answers
45 views
How to sum the output of two commands and save it to a file?
I have two kfsql commands that get total count of users.
I need these two command outputs to be added up and printed to a file.txt
I tried:
var1= getdatabase1
var2= getdatabase2
echo "$var1"
echo ...
1
vote
1answer
26 views
Bash - Catch input for a substituted command stored in variable
How would I be able to catch the input for a substituted command stored in a variable?
Example:
How would I be able to catch the input for the following command?
bar_foo=$(openssl passwd -1 -salt ...
0
votes
3answers
49 views
Why is the array empty after the while loop? [duplicate]
I try to initialize an array in bash-4.2 next way:
ring=()
ls -las | tail -n +4 | while read line
> do
> ring+=("$line")
> echo ${ring[-1]}
> done
3924 -rw-r--r-- 1 username group 4015716 ...
1
vote
1answer
24 views
Which shells have functions where “local” does not alter exported variables for child processes?
In the example below, an exported variable is re-set as local in a function. Bash, Zsh, Fish don't pass on the original value to the child process. Are there any shells that make local affect the ...
1
vote
1answer
23 views
Error with find when using -newerct values stored in variables
I'm trying to create a bash function that will use a simple file such as
sample.txt
start=22 Mar 2016 10:00
end=22 Mar 2016 12:09
...and find files that I have installed to /usr/local within the ...
3
votes
2answers
33 views
How is the return status of a variable assignment determined?
I have seen constructs in scripts such as this:
if somevar="$(somecommand 2>/dev/null)"; then
...
fi
Is this documented somewhere? How is the return status of a variable determined and how does ...
0
votes
3answers
28 views
How to get help for bash variables use from a command line?
Bash has some special or predefined variables, such as $? and $#.
How to know the meaning of those variables use build in command instead of searching online web pages?
I have try to use this:
...
0
votes
1answer
15 views
How can I get a variables datatype in zsh?
For example zsh uses the variable $fpath to define include directories.
How can I tell what type of variable $fpath is?
i.e. is fpath a
string
number
numeric array
associative array
-1
votes
2answers
51 views
Finding the number of files in a folder [duplicate]
How can I find a number of files in a folder, assign it to a variable, then echo that variable, all in one command line?
0
votes
1answer
29 views
how can we change the DISPLAY variable in linux [closed]
What is the command to change the DISPLAY display variable in Linux, because while installation of a program I am getting the error as in the attached screen shot, so please help me how to get it out ...
3
votes
3answers
49 views
bash array with variable in the name
I'll appreciate your help with the following issue:
I'm trying to set an array which contains a variable as part of the array name, example: Arr_$COUNTER (where $COUNTER is changed based on a loop ...
1
vote
0answers
28 views
Evaluate variables' value in Kickstart file
I am trying to make a Kickstart install of a CentOS 7 VM interactive, by asking for user input in the %pre-install script, as described here.
So far I've managed to get user-entered values and store ...
0
votes
1answer
18 views
How to define a shell variable as equal to the version of Vim presently installed?
I am intending to write a shell script (if specifics are required, it will be executed in Zsh) that will determine the latest Vim patch via running:
git pull origin master
vernew=$(git describe ...
1
vote
1answer
29 views
Scope of variables in a process substitution
I have a command which takes two arguments. Assume we want to create both arguments by process substitution:
cat <(var=123; echo $var) <(echo $var)
What has to be done, to make $var available ...
0
votes
2answers
43 views
Which location does shell assign normal variable?
As you know, bash shell itself is also process.
If I use command export a=c, then shell dynamically allocates variable a into location where environment variables are reside.(This environment section ...
0
votes
2answers
30 views
echoing a variable inside a variable
In my environment, the following variable is set:
X=/home
so echo $X gives me /home
Now I set Y=$X
echo $Y gives me $X.
If I want to get /home using Y is it possible?
5
votes
2answers
66 views
How to store a path built with wildcards and containing with spaces into a variable
Here's the situation (I'm on a Mac, OS X El Capitan):
# This works:
$ cd /Applications/Adobe\ Illustrator*/Cool\ Extras.localized/en_US/Templates/;
# These do not work:
$ ...
0
votes
0answers
12 views
Export variable failed when I was compiling NETCDF
I'm compiling NETCDF on Linux.
After configure, make,make install, I have already install NETCDF on
/disk3/lly/lib/netcdf-4.1.3.
Then, using vim ~/.bashrc,edit:
export ...
1
vote
0answers
23 views
How do you pass variables to jsc/javascript?
I have a few javascript things that I am running from the Terminal by passing them to jsc, with <<<. (javascript is an alias to ...
1
vote
2answers
37 views
Running Emacs through the value of the bash variable
How would I add a value to a new variable in bash, so that when I echo the variable Emacs would run?
5
votes
2answers
95 views
In bash script, what's the different between declare and a normal variable?
In bash scripting:
we create variable just name it:
abc=ok
or we can use declare
declare abc=ok
what's the different ?
and why bash make so many ways to create variable?
0
votes
1answer
39 views
Create command line variables with PATH
As I am more of a web guy, i need a little help with this one, so I will explain what I am trying to do before I ask.
I am creating batch script that will:
GET request from an external server (json ...
0
votes
1answer
35 views
How to set up a pre-defined variable with multiple directory paths to use with the find command
I am looking to have a script delete files that are older than 90 days in certain directories. As in, there are 8 directories that have different paths to them.
I can run the find command on one ...
8
votes
4answers
245 views
dirname and basename vs parameter expansion
Is there any objective reason to prefer one form to the other? Performance, reliability, portability?
filename=/some/long/path/to/a_file
parentdir_v1="${filename%/*}"
parentdir_v2="$(dirname ...
1
vote
1answer
47 views
Use sed to retrieve variable from 1 file and place it in another
I need to use sed to retrieve a variable form within a file name. I am updating a previous code:
cat /directory/filename1.xml | sed -e "s/XYZABC/${c}/g" > /directory/filename2.xml
The value for ${c} ...
16
votes
6answers
572 views
Should variables be quoted when executed?
The general rule in shell scripting is that variables should always be quoted unless there is a compelling reason not to. For more details than you probably want to know, have a look at this great ...
0
votes
1answer
49 views
How do I write a Bash script that will ask users to define a variable?
I am presently modifying this shell script to turn it into a shell script for installing Arch Linux, with custom username(s), password(s), etc. At the moment I am wondering what I need to do in order ...
2
votes
2answers
48 views
Exported variables inside ssh session are empty
I am trying to export a variable inside a ssh session and reference the variable in the next write command.
sshpass -p "password" ssh -t -t my-box <<EOF
export newUrl="this is a url"
sudo ...
2
votes
5answers
42 views
Help on edit a sed statement
I'm writing a script to change on the fly the firefox home page through a text variable:
sed -i 's|\("browser.startup.homepage",\) "\(.*\)"|\1 "$ddrs"|' /home/max/.mozilla/firefox/*.default/prefs.js
...
3
votes
4answers
444 views
Sum of all Integers between two numbers
I would like to type in two numbers and get the sum of all integers between those two numbers, inclusive.
For example:
./sum1 2 5
should yield
sum: 14
because 2+3+4+5 = 14
Here's what I have ...
0
votes
1answer
34 views
Script with variable in path
I'm not entirely sure where to ask or how to formulate this question with correct terminology.
I have script here for managing a game (minecraft) server for the user (bukkit).
I've cut out some ...
1
vote
1answer
36 views
Assign path to variable which does not exist
In an effort of keeping things DRY, I am trying to assign a path to a variable that may not exist and have the following script which returns:
/apps/tmp: No such file or directory
#!/bin/bash
...
3
votes
5answers
87 views
Bash - Store Color Codes in Variable
How do I store colored text in a variable and print it with color later?
I never see the answer to this question in 100 searches it's all about PS1 prompts, or inline printf's or using data from ls ...
0
votes
1answer
51 views
Where is my .sh script syntax error(s)?
Trying to run a small simple script to pull the java -version information from an AIX system's several java64 folders piped into an output/log file using the system's hostname but can't seem to get it ...
1
vote
1answer
40 views
Relation between shell start up processes and environment of parent process
"How are shell variables related to the environment that a process started by the shell has on start-up?"
I read If processes inherit the parent's environment, why do we need export?
My current ...
1
vote
1answer
72 views
Inserting variables in a command within a shell script
I'm attempting to write an automated script which will update the IP address for my Raspberry Pi within my /etc/hosts file.
I'm able to execute this line just fine,
IP=`sudo nmap -sP 10.61.4.0/24 | ...
1
vote
1answer
48 views
Linux bash script input without using “read” [closed]
I need to create a bash script where a single argument is passed by the user (without using the "read" input option) at the terminal command line that creates a directory with that name, or otherwise ...
0
votes
3answers
144 views
Passing Variable from one script to another
How can I pass a variable between scripts?
Example: I have two test scripts:
-- test2.sh
#!/bin/bash
echo "this is test2.sh"
echo "varname is $varname"
echo end
-- tes1.sh
#!/bin/bash
...
2
votes
1answer
55 views
Run a command stored in a variable to echo into a file
How can I get the stored command to work for the following scenario:
CMD='echo "test" >> test.txt'
$CMD
It will work for other scenarios like:
CMD='mkdir test'
$CMD
1
vote
2answers
69 views
How to replace values in a string using sed but keep the string intact
How to replace values in a string using sed but keep the string intact?
For example echo "01XX1234"
I'm looking to replace XX with a hex value and leave the 01 and the 1234 intact. I've tried every ...
0
votes
0answers
17 views
Difference between “$@” and “$*” when passing arguments to bash function [duplicate]
I'm having hard time understanding difference between $@ and $* when passing them to functions.
Here is example:
function a {
echo "-$1-" "-$2-" "-$3-";
}
function b {
a "$@"
}
function c ...
-3
votes
1answer
27 views
Output the result of a variable
I have an if statement and I want in one case to add one to a variable v and in the other case to a variable inv.
I did the following
v=$((v + 1)) and inv=$((inv + 1))
I want to outputs the results of ...
1
vote
2answers
68 views
How to set multiple values to the same variable in UNIX?
I am trying to have a script give me the output of multiple words and variations of the words. I tried putting in the -o for the variable, quoting the words, piping them together. The words for each ...
1
vote
1answer
60 views
Bash variables - Any extract tricks based on the order?
Instead of:
var1=foofoo
var2=barbar
var3=jarjar
Is there some trick I can to get the variable based on the order it was set in?
var=foo
var=bar
var=jar
echo $var2
bar
(I know the var ...
2
votes
3answers
61 views
List variables with prefix where the prefix is stored in another variable
I'm trying to list all the variables with a certain prefix, but that prefix is dynamically determined. For example:
prefix=apple_
apple_one=a1
apple_two=a2
If I simply do:
echo ${!apple_@}
I ...
1
vote
3answers
48 views
Pipes vs variable assignment
In what ways are pipes different from variable assignments?
I know you can't use null bytes. What other examples are there?
What about for piping in something like the following yes | cat?
I notice ...
0
votes
1answer
65 views
grep a variable within an if statement
Maybe I am approaching this the wrong way, so I am open for suggestions. I am trying to avoid adding the output of INSTALLED_LIST to a file. I wish to use it within a variable.
Basically, I want to ...
0
votes
3answers
67 views
Ignore certain characters when comparing variables?
For example, If this is my script:
if [[ $yesno == "What's going on" ]]; then
Then how do I make it Ignore ', ?, , and . for example?
So basically Whats going on, What's going on, What's going on? ...
