Set Variables in Bash Script

Unable to set variables in bash script

Assignment in bash scripts cannot have spaces around the = and you probably want your date commands enclosed in backticks $():

#!/bin/bash
folder="ABC"
useracct='test'
day=$(date "+%d")
month=$(date "+%B")
year=$(date "+%Y")
folderToBeMoved="/users/$useracct/Documents/Archive/Primetime.eyetv"
newfoldername="/Volumes/Media/Network/$folder/$month$day$year"
ECHO "Network is $network" $network
ECHO "day is $day"
ECHO "Month is $month"
ECHO "YEAR is $year"
ECHO "source is $folderToBeMoved"
ECHO "dest is $newfoldername"
mkdir $newfoldername
cp -R $folderToBeMoved $newfoldername
if [-f $newfoldername/Primetime.eyetv]; then rm $folderToBeMoved; fi

With the last three lines commented out, for me this outputs:

Network is 
day is 16
Month is March
YEAR is 2010
source is /users/test/Documents/Archive/Primetime.eyetv
dest is /Volumes/Media/Network/ABC/March162010

How do I run a bash script and set variables?

To set environment variables that will be inherited by the script process, put the assignments at the beginning:

dbname="hello" dbuser="admin" bash wp.sh

How to get set variable in a shell script

By default variables declared without export are not passed to subprocesses.

 export s1="hello stackoverflow"

if it was set not by you , just export it:

export s1

./test.sh

---output

hello stackoverflow
s1='hello stackoverflow'

And of course use quotes:

#!/bin/sh
echo "$s1"
hello=$( set | grep s1 )
echo "$hello

bash script with variables not getting set

Child shells cannot affect the environment of their parent. If you want the script to affect the parent's environment, you need to:

source ./env.sh

So what's going on? When you run a bash script, either by bash env.sh or env.sh, you're spawning a program with its own environment, an environment that's divorced from its parent. But, when you run the commands contained in the script at the command line, or using source, there is no spawned environment.

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Edit to address @syme's comment. Bash scripts meant to be read using source are often pure configuration, containing only assignments and calculations. It's possible to also make them a little more helpful and self-documenting with a clever she-bang hack like:

#!/bin/echo USAGE: source 
# Default configuration file for the Frobnicator package.

FOO=bar
BAR=$(stat /baz)
[[ -f /baz ]] && BAZ=file || BAZ=

export FOO BAR BAZ

Making a bash script meant for configuration look like a configuration script, you help future maintainers. You also help yourself my modularizing your script code into distinct parts, each part with its one unique function.

As a side note, please don't export on the same line as you assign.

bash script - unable to set variable with double quotes in value

In bash (and other POSIX shells), the following 2 states are equivalent:

_account=foo
_account="foo"

What you want to do is to preserve the quotations, therefore you can do the following:

_account='"foo"'

How do I set a variable to the output of a command in Bash?

In addition to backticks `command`, command substitution can be done with $(command) or "$(command)", which I find easier to read, and allows for nesting.

OUTPUT=$(ls -1)
echo "${OUTPUT}"

MULTILINE=$(ls \
   -1)
echo "${MULTILINE}"

Quoting (") does matter to preserve multi-line variable values; it is optional on the right-hand side of an assignment, as word splitting is not performed, so OUTPUT=$(ls -1) would work fine.

Bash: Creating a shell variable in a bash script that I can access from command line

You have to export the variable for it to exist in the newly-execed shell:

#!/bin/bash
export mypath=$(pwd)
cd $1
echo $mypath
exec bash

Passing bash script variables to .yml file for use as child and subdirectories

Does envsubst solve your problem?

For example, if I have a test-yaml.yml that contains $foo:

cat test-yaml.yml 

output:

general:
  $foo: argument_from_bash_script
  rawdatadir: '/some/data/directory/$foo'
  input: '/my/input/directory/$foo/input'
  output: '/my/output/directory/$foo/output'

You can replace $foo inside test-yaml.yml with shell variable $foo by envsubst:

export foo=123
envsubst < test-yaml.yml 

output:

general:
  123: argument_from_bash_script
  rawdatadir: '/some/data/directory/123'
  input: '/my/input/directory/123/input'
  output: '/my/output/directory/123/output'

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