Questions tagged [eval]

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1answer
28 views

Script using data/input which contains variable names [duplicate]

So I have a file "Directories.dat" that contains a list of directories for a script to read that runs on multiple machines. Due to this, the list of directories in the file is often defined ...
0
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2answers
49 views

eval variable=command in the background

I have the following code for name in a b c d; do for i in {01..12}; do eval test_${name}_{i}=`some command` done done I am trying to do the assignments in the background but it doesn'...
3
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1answer
235 views

How to conditionally redirect the output to files based on variable in bash

I'm trying to use eval command to eval a comment -- I'm not sure if this is the right way to do it. Example: i=?? (What I want here is either a #, to comment what's after, or blank) somecommand arg1 ...
0
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1answer
41 views

How to export lines from other file into current shell

I have this content in a file called foo.env: foo=bar and then I want to read that file and export the lines to the shell: for line in $(cat ./foo.env); do eval export $line done but when I run ...
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2answers
137 views

How can I write an `eval` command containing a new line into one line?

Since I need to set and use alias in the same line in bash, I would like to use Hauke Laging's workaround: eval 'alias df5=df df5 -h' (I took df and df5 for the sake of the example. I am aware that ...
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0answers
18 views

Why running eval from cli works, but running script with eval inside it, it doesn't? [duplicate]

Why when I run eval $(keychain --quiet ~/.ssh/id_rsa) from cli it works, but if I try to do same from the script it doesn't work and $SSH_AUTH variables are not present?
0
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1answer
55 views

Generating content stored under a dynamic variable in Shell Script

I am stuck with the below code and any help would be greatly appreciated: I am trying to assign contents inside a dynamically generated variable to another variable. But instead of the value of the ...
0
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0answers
48 views

Can I avoid using eval in alias re-definition?

My system: Linux Mint 19.3. My default shell: Bash. Problem: I do not like using eval (man page) if unnecessary. Question: Is there another way of redefining stored alias, which I currently do as ...
2
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2answers
118 views

building an alias from a function

I need a lot of different aliases to create ssh tunnels to different servers. To give you a few of them: alias tunnel_1='autossh -M 20000 -N -L 8080:localhost:8080 -N -L 9200:localhost:9200 -N -L ...
12
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2answers
404 views

Behaviour of “eval” under “set -e” in conditional expression

Consider the commands eval false || echo ok echo also ok Ordinarily, we'd expect this to execute the false utility and, since the exit status is non-zero, to then execute echo ok and echo also ok. ...
2
votes
1answer
371 views

How to execute something in current shell [duplicate]

I want to create a bash script or something similar that I can execute in the current shell: echo '#!/bin/bash export foo="bar" ' > zoom.sh but if I want to run this script in the current ...
0
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1answer
222 views

Weird behavior of su command

Everytime I run su command on this box, I constantly see the weird messages below. Switching user do eventually continue, but why are these messages showing? <Server>:~ # su - -bash: eval: line ...
1
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1answer
52 views

Why does this bash idiom require eval?

Why does this produces _results=""... _results="$( grep ${_gopts[@]} )" And this produces the desired _results (list of SSHFS entries in fstab)... _results="$( eval grep ${_gopts[@]} )" The _gopts ...
0
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1answer
44 views

How to check “eval” command?

My code docker-machine create --driver virtualbox dev VBoxManage list vms "minikube" {9c326ed5-faf4-42fe-acda-bf3a283f1a74} "kalinew" {de6de631-0d51-4638-b967-66db463cbf05} "dev" {84a116bf-02b9-...
1
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3answers
1k views

Get return code of first piped command using eval?

I wish to execute different commands and check the return code afterwards before moving to the next steps in the script. At the same time I also wish to log the output of the executed commands to a ...
0
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1answer
2k views

Trying to export a path from inside a bash script [duplicate]

I am trying to put my whole environment set up into a single bash file. I am only hitting one issue. When I try to export a new path from inside the file it is not setting the path in the environment ...
0
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2answers
695 views

eval ssh command in variable

I am trying to execute commands via ssh remotely. But I have the calling command saved as variable such as: SSH_CMD="ssh -i path_to/identity" SSH_USER=user SSH_DST=server dir1=dir1 dir2=dir2 now if ...
5
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1answer
1k views

File with parentheses/brackets in working directory causes eval error

I encountered a strange bug today, when running a script in a directory containing a directory with parentheses in it, such as a(). Minimal working example I managed to reduce the bug to the ...
-3
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2answers
108 views

Loop through filenames without eval [closed]

In a shell script, if we want to loop over certain filenames, which we would get by shell globbing, as for example all MKV-files in all sub-directories starting with string "Example" – how can we do ...
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2answers
1k views

Eval and exec with variable substitution

I'd like to execute a statement to start a server. For that I have an environment variable to determine which server is to be started. I was given this command as a starting point: eval "exec ...
2
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2answers
350 views

Bash: How to kill eval if the process that receives its output terminates

I have a little ugly bash script on my Ubuntu machine that contains the lines: search_command="find -L $(printf "%q" "$search_folder") \( ! -regex '.*/\..*/..*' \) -mindepth 1 2> /dev/null" for i ...
1
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1answer
1k views

dollar sign inside eval string in bash

I have hundreds of sub-directories which contain a dollar sign (i.e., $) as the 1st character in their names, each of which needs to be visited. These sub-directories can not be renamed. The bash ...
1
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1answer
179 views

zsh: A prefix function that runs the rest of the line with no alias expansion

I am thinking of: function noalias() { setopt localoptions noexpandalias "$@" } But I don't know what the last line should be. eval "${*:q}"? eval "$@"? eval "${@:q}"? "${@:q}"? ${@:q}? $@? (...
2
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2answers
440 views

Does `eval` apply the shell to the redirection part of the following command?

When use eval on a command, does eval apply the shell twice to the redirection part of the command? Suppose the filename in the redirection contains a whitespace, if eval applies all the steps of ...
1
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2answers
2k views

Why is eval not working with command substitution? [closed]

I have this command $("${DIR}/test.py" "$1") the output of which is export SOME_VAR="hello world" export ANOTHER_VAR="hello" But eval $("${DIR}/test.py" "$1") seems to do nothing. What am I ...
6
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1answer
2k views

eval vs. pipe through bash

What is the difference between using: eval 'echo "foo"' and echo 'echo "foo"' | bash is there any?
-3
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1answer
152 views

Eval not working

i try run this code to get random number but eval seems not working this is my code #!/bin/bash # Sequencia alfanumerica de 12 carateres aleatoriamente (maiusculas e minusculas) file="/home/...
1
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2answers
97 views

cksum files using substituted variable string as a pattern

Can I avoid eval in the below example or is there no other way? The list of files on variable is dynamic, and I want to cksum all of them. There are many other files in the directory, but they should ...
2
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3answers
157 views

Get contents of passing string from a script

I would like to get, in the output, the content of KW0_TEXT and KW1_TEXT from the "for" of this script: #!/bin/sh STRS=" KW0 KW1 " KW0_TEXT="text text text" KW1_TEXT="text text text text" for str ...
1
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1answer
2k views

Will “dircolors” work here instead of “ eval `”dircolors`“` ”?

I was checking .bashrc to set colors for ls comand and found this export SHELL='/bin/bash' export LS_OPTIONS='--color=auto' eval "`dircolors`" alias ls='ls $LS_OPTIONS' Will there be any problem ...
0
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3answers
953 views

diff two files from a command output [closed]

I have a bunch of xml file in the current directory. Problem 1. As far as I have read eval returns the results and stores it in a variable. But I get an error with the below command find ./ -name '...
2
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2answers
5k views

Why is using eval necessary to pass quoted arguments

I have the following example. #!/bin/bash ARGUMENTS="-executors 1 -description \"The Host\" " # call1 # error: parameter Host" is not allowed java -jar swarm-client.jar $ARGUMENTS # call2 # ...
9
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2answers
16k views

return value from eval

The bash manual states: eval [arg ...] The args are read and concatenated together into a single com- mand. This command is then read and executed by the shell, and ...
6
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4answers
35k views

bash + read variables & values from file by bash script

I have the following file variable and values # more file.txt export worker01="sdg sdh sdi sdj sdk" export worker02="sdg sdh sdi sdj sdm" export worker03="sdg sdh sdi sdj sdf" I perform source in ...
1
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2answers
572 views

eval not evaluating echo? [duplicate]

I'm trying to write something that stores an API access token in a bash variable, so I'm modelling it on ssh-agent, where you use eval. ssh-agent If you run ssh-agent by itself, it outputs something ...
17
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4answers
31k views

How can I list all user names and/or home directories?

I want to list all the users dirs on the machine.Usually, I will do: ls -l /home But I use it in a script that will be deployed on others machines and maybe on that machines they don't call it home (...
1
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1answer
330 views

how to evaluate an dynamically generated if elif else statement in shell

im having trouble getting a dynamically generated shell function to evaluate properly (by evaluate i mean "eval" command) this is the desired statement to be evaluated when ran (except the output ...
5
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2answers
3k views

Bash: Why is used eval and shift in a script that parses command line arguments?

As I was looking this answer https://stackoverflow.com/a/11065196/4706711 in order to figure out on how to use parameters like --something or -s some questions rised regarding the answer's script : #!...
0
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1answer
48 views

Evaluate part of a text line

I have an expression of the form @(<date calculation>) that I want to replace with the result of date +%s --date "now<date calculation>". So for example @(-1 day) would be replaced with ...
92
votes
1answer
27k views

Why eval the output of ssh-agent?

In order to run ssh-agent I have to use: eval $(ssh-agent) Why is it necessary to eval the output of ssh-agent? Why can't I just run it?
0
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1answer
103 views

Process Substitution (e. g. $(somecommand) ) In A Nutshell

On my shell from home directory on mac, I run the following eval "ls" and this just shows me the directories. But if I run eval "$(ls)" I get the following output: zsh: command not found: ...
4
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1answer
2k views

Can bash expand a quoted and/or escaped string variable into words?

I have a bash shell variable containing a string formed of multiple words delimited by whitespace. The string can contain escapes, such as escaped whitespace within a word. Words containing whitespace ...
0
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1answer
714 views

why doesn't eval declare in a function work in bash?

Tracking down strange behavior a bash script resulted in the following MWE: set -o errexit set -o nounset set -x my_eval() { eval "$1" } my_eval "declare -A ASSOC" ASSOC[foo]=bar echo success ...
2
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3answers
982 views

Using the eval command twice

Suppose: a=b; b=c; c=d Then eval echo \$$a produces the output: c If we want to extract the output d using just input a, I tried the following way: (i) eval echo \$(eval echo \$$a) produces the ...
0
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3answers
1k views

Is eval implemented by creating a shell process to evaluate the following command?

In eval <command>, how does eval evaluate the following command? does eval create a shell subprocess to evaluate <command>? If not, does eval rely on the current shell process to ...
4
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1answer
286 views

How to deal with insecurity of `eval` evaluating external input in a script?

Binaryzebra said this script is evaluating external input, a highly insecure practice. What are some ways to deal with or even replace eval evaluating external inputs in a script? Thanks.
0
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1answer
876 views

script set command output to variable [duplicate]

I'm writing a simple script that prompts the user for information and saves it as a variable to be passed as arguments in another command. One of the variables stores a path which may include a space. ...
8
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1answer
5k views

How to save an alias of an eval $(other_comand) command

I've been using docker for a while and there's a command I write each time I boot up my docker: eval $(docker-machine env) I know eval shouldn't be used unless necessary, but it's mentioned by the ...
0
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2answers
2k views

Error when eval a for-loop

I am writing a script which accepts two arguments: #! /bin/bash eval for i in {$1..$2}; do echo $i; done I run it like: $ ./myscript 0002 0010 syntax error near unexpected token `do' Why is ...
6
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3answers
7k views

Why and when should eval use be avoided in shell scripts? [duplicate]

Many answers and comments on this site mention that one should generally avoid using eval in shell scripts. Often these comments are addressed to beginners. I've seen mention of security issues and ...