I need your help with a bash >= 4 script I'm writing.
I am retrieving some files from remote hosts to back them up.
I have a for loop that iterate through the hosts and for each one tests connection and the start a function that retrieves the various files.
My problem is that I need to know what gone wrong (and if), so I am trying to store OK or KO values in an array and parse it later.
This is the code:
...
for remote_host in $hosts ; do
short_host=$(echo "$remote_host" | grep -o '^[^.]\+')
declare -A cluster
printf "INFO: Testing connectivity to %s... " "$remote_host"
if ssh -q "$remote_host" exit ; then
printf "OK!\n"
cluster[$short_host]="Reacheable"
mkdir "$short_host"
echo "INFO: Collecting files ..."
declare -A ${short_host}
objects1="/etc/krb5.conf /etc/passwd /etc/group /etc/fstab /etc/sudoers /etc/shadow"
for obj in ${objects1} ; do
if file_retrieve "$user" "$remote_host" "$obj" ; then
-> ${short_host}=["$obj"]=OK
else
${short_host}=["$obj"]=KO
fi
done
...
So I'm using an array named cluster to list if the nodes were reacheable, and another array - named after the short name of the node - to list OK or KO for single files.
On execution, I got the following error (line 130 is the line I marked with the arrow above):
./test.sh: line 130: ubuntu01=[/etc/krb5.conf]=OK: command not found
I think this is a synthax error for sure, but I can't fix it. I tried a bunch of combinations without success.
Thanks for your help.
Since the array name is contained in a variable short_list, you need eval to make the assignment work:
${short_host}=["$obj"]=OK
Change it to:
eval ${short_host}=["$obj"]=OK
eval ${short_host}=["$obj"]=OK
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Single line while loop updating array
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I have encountered a very curious problem, while trying to learn bash.
Usually trying to print an echo by simply parsing the variable name like this only outputs the first member Hello.
#!/bin/bash
declare -a test
test[0]="Hello"
test[1]="World"
echo $test # Only prints "Hello"
BUT, for some reason this piece of code prints out ALL members of the given array.
#!/bin/bash
declare -a files
counter=0
for file in "./*"
do
files[$counter]=$file
let $((counter++))
done
echo $files # prints "./file1 ./file2 ./file3" and so on
And I can't seem to wrap my head around it on why it outputs the whole array instead of only the first member. I think it has something to do with my usage of the foreach-loop, but I was unable to find any concrete answer. It's driving me crazy!
Please send help!
When you quoted the pattern, you only created a single entry in your array:
$ declare -p files
declare -a files=([0]="./*")
If you had quoted the parameter expansion, you would see
$ echo "$files"
./*
Without the quotes, the expansion is subject to pathname generation, so echo receives multiple arguments, each of which is printed.
To build the array you expected, drop the quotes around the pattern. The results of pathname generation are not subject to further word-splitting (or recursive pathname generation), so no quotes would be needed.
for file in ./*
do
...
done
I am trying to loop through an array of directories using a bash script so I can list directories with their timestamp, ownership etc using ls -arlt. I am reviewing bash so would like some feedback.
It works with declare -a for those indirect references but for each directory it outputs and extra directory from the /home/user.
I tried to use declare -n and declare -r for each directory and doesn't work.
#!/bin/bash
# Bash variables
acpi=/etc/acpi
apm=/etc/apm
xml=/etc/xml
array=( acpi apm xml )
# Function to display timestamp, ownership ...
displayInfo()
{
for i in "${array[#]}"; do
declare -n curArray=$i
if [[ -d ${curArray} ]]; then
declare -a _acpi=${curArray[0]} _apm=${curArray[1]} _xml=${curArray[2]}
echo "Displaying folder apci: "
cd $_acpi
ls -alrt
read -p "Press enter to continue"
echo "Displaying folder apm: "
cd $_apm
ls -alrt
read -p "Press enter to continue"
echo "Displaying folder xml: "
cd $_xml
ls -alrt
read -p "Press enter to continue"
else
echo "Displayed Failed" >&2
exit 1
fi
done
}
displayInfo
exit 0
It outputs an extra directory listing the /home/user and don't want that output.
There are a lot of complex and powerful shell features being used here, but in ways that don't fit together or make sense. I'll go over the mistakes in a minute, first let me just give how I'd do it. One thing I will use that you might not be familiar with is indirect variable references with ${!var} -- this is like using a nameref variable, but IMO it's clearer what's going on.
acpi=/etc/acpi
apm=/etc/apm
xml=/etc/xml
array=( acpi apm xml )
displayInfo()
{
for curDirectory in "${array[#]}"; do
if [[ -d ${!curDirectory} ]]; then
echo "Displaying folder $curDirectory:"
ls -alrt "${!curDirectory}"
read -p "Press enter to continue"
else
echo "Error: ${!curDirectory} does not exist or is not a directory" >&2
exit 1
fi
done
}
displayInfo
(One problem with this is that it does the "Press enter to continue" thing after each directory, rather than just between them. This can be fixed, but it's a little more work.)
Ok, now for what went wrong with the original. My main recommendation for you would be to try mentally stepping through your code to see what it's doing. It can help to put set -x before it, so the shell will print its interpretation of what it's doing as it runs, and see how it compares to what you expected. Let's do a short walkthrough of the displayInfo function:
for i in "${array[#]}"; do
This will loop over the contents of array, so on the first pass through the loop i will be set to "acpi". Good so far.
declare -n curArray=$i
This creates a nameref variable pointing to the other variable acpi -- this is similar to what I did with ${! }, and basically reasonable so far. Well, with one exception: the name suggests it's an array, but acpi is a plain variable, not an array.
if [[ -d ${curArray} ]]; then
This checks whether the contents of the acpi variable, "/etc/acpi" is the path of an existing directory (which it is). Still doing good.
declare -a _acpi=${curArray[0]} _apm=${curArray[1]} _xml=${curArray[2]}
Here's where things go completely off the rails. curArray points to the variable acpi, so ${curArray[0]} etc are equivalent to ${acpi[0]} etc. But acpi isn't an array, it's a plain variable, so ${acpi[0]} gets its value, and ${acpi[1]} and ${acpi[2]} get nothing. Furthermore, you're using declare -a (declare arrays), but you're just assigning single values to _acpi, _apm, and _xml. They're declared as arrays, but you're just using them as plain variables (basically the reverse of how you're using curArray -> acpi).
There's a deeper confusion here as well. The for loop above is iterating over "acpi", "apm", and "xml", and we're currently working on "acpi". During this pass through the loop, you should only be working on acpi, not also trying to work on apm and xml. That's the point of having a for loop there.
Ok, that's the main problem here, but let me just point out a couple of other things I'd consider bad practice:
cd $_apm
ls -alrt
Using a variable reference without double-quotes around it like this invites parsing confusion; you should almost always put double-quotes, like cd "$_apm". Also, using cd in a script is dangerous because if it fails the rest of the script will execute in the wrong place. In this case, _apm is empty, so without double-quotes it's equivalent to just cd, which moves to your home directory. This is why you're getting that result. If you used cd "$_apm" it would get an error instead... but since you don't check for that it'll go ahead and still list an irrelevant location.
It's almost always better to avoid cd and its complications entirely, and just use explicit paths, like ls -alrt "$_apm".
echo "Displayed Failed" >&2
exit 1
Do you actually want to exit the entire script if one of the directories doesn't exist? It'd make more sense to me to just return 1 (which exits just the function, not the entire script), or better yet continue (which just goes on to the next iteration of the loop -- i.e. the next directory on the list). I left the exit in my version, but I'd recommend changing it.
One more similar thing:
acpi=/etc/acpi
apm=/etc/apm
xml=/etc/xml
array=( acpi apm xml )
Is there any actual reason to use this array -> variable name -> actual directory path system (and resulting indirect expansion or nameref complications), rather than just having an array of directory paths, like this?
array=( /etc/acpi /etc/apm /etc/xml )
I left the indirection in my version above, but really if there's no reason for it I'd remove the complication.
After struggling with this issue for several hours and searching here and failing to come up with a matching solution, it's time to ask:
In bash (4.3) I'm attempting to do a combination of the following:
Create an array
For loop through the values of the array with a command that isn't super fast (curl to a web server to get a value), so we background each loop to parallelize everything to speed it up.
Set the names of the values in the array to variables assigned to values redirected to it from a command via "read"
Background each loop and get their PID into a regular array, and associate each PID with the related array value in an associative array so I have key=value pairs of array value name to PID
Use "wait" to wait for each PID to exit 0 or throw an error telling us which value name(s) in the array failed to exit with 0 by referencing the associative array
I need to be able export all of the VAR names in the original array and their now-associated values (from the curl command results) because I'm sourcing this script from another bash script that will use the resulting exported VARs/values.
The reason I'm using "read" instead of just "export" with "export var=$(command)" or similar, is because when I background and get the PID to use "wait" with in the next for loop, I actually (incorrectly) get the PID of the "export" command which always exits 0, so I don't detect an error. When I use read with the redirect to set the value of the VAR (from name in the array) and background, it actually gets the PID of the command and I catch any errors in the next loop with the "wait" command.
So, basically, this mostly appears to work, except I realized the "read" command doesn't actually appear to be substituting the variable to the array name value properly in a way that the redirected command sends its output to that name in order to set the substituted VAR name to a value. Or, maybe the command is just entirely wrong so I'm not correctly redirecting the result of my command to a VAR name I'm attempting to set.
For what it's worth, when I run the curl | python command by hand (to pull the value and then parse the JSON output) it is definitely succeeding, so I know that's working, I just can't get the redirect to send the resulting output to the VAR name.
Here's a example of what I'm trying to do:
In parent script:
# Source the child script that has the functions I need
source functions.sh
# Create the array
VALUES=(
VALUE_A
VALUE_B
VALUE_C
)
# Call the function sourced from the script above, which will use the above defined array
function_getvalues
In child (sourced) script:
function_getvalues()
{
curl_pids=( )
declare -A value_pids
for value in "${VALUES[#]}"; do
read ${value} < <(curl -f -s -X GET http://path/to/json/value | python3 -c "import sys, json; print(json.load(sys.stdin)['data']['value'])") & curl_pids+=( $! ) value_pids+=([$!]=${value})
done
for pid in "${curl_pids[#]}"; do
wait "$pid" && echo "Successfully retrieved value ${value_pids[$pid]} from Webserver." || { echo "Something went wrong retrieving value ${value_pids[$pid]}, so we couldn't get the output data needed from Webserver. Exiting." ; exit 1 ; }
done
}
The problem is that read, when run in the background, isn't connected to a standard in.[details] Consider this simplified, working example with comment how to cripple it:
VALUES=( VALUE_A VALUE_B )
for value in "${VALUES[#]}"; do
read ${value} < <(echo ${RANDOM}) # add "&" and it stops working
done
echo "VALUE_A=${VALUE_A}"
echo "VALUE_B=${VALUE_B}"
You might be able to do this with coproc, or using read -u with automatic file descriptor allocation, but really this is a job for temporary files:
tmpdir=$(mktemp -d)
VALUES=( VALUE_A VALUE_B )
for value in "${VALUES[#]}"; do
(sleep 1; echo ${RANDOM} > "${tmpdir}"/"${value}") &
done
for value in "${VALUES[#]}"; do
wait_file "${tmpdir}"/"${value}" && {
read -r ${value} < "${tmpdir}"/"${value}";
}
done
echo "VALUE_A=${VALUE_A}"
echo "VALUE_B=${VALUE_B}"
rm -r "${tmpdir}"
This example uses wait_file helper, but you might use inotifywait if you don't mind some dependencies on OS.
I'm stucked on a bash script.
I'm having a config.ini files like this :
#Username
username=user
#Userpassword
userpassword=password
And i'm looking in a bash script to extract this information and put it in a associative array. My script looks like :
declare -A array
OIFS=$IFS
IFS='='
grep -vE '^(\s*$|#)' file | while read -r var1 var2
do
array+=([$var1]=$var2)
done
echo ${array[#]}
But the array seems to be empty because the commande echo ${array[#]} gives no output.
Any idea why me script don't work ? Thanks for your help and sorry for my bad english.
Common error - "grep | while" causes the while loop to be executed in a separate shell and the variables inside the loop are not global to your shell. Use a here string instead:
while read -r var1 var2
do
array+=([$var1]=$var2)
done <<< $(grep -vE '^(\s*$|#)' file)
Assuming the file can be trusted (ie the content is regulated and known), the simplest method would be to source the ini file and then directly use the variable names within the script:
. config.ini
You can either use the period (.) as above or the source builtin command
New to StackOverflow and new to bash scripting. I have a shell script that is attempting to do the following:
cd into a directory on a remote machine. Assume I have already established a successful SSH connection.
Save the email addresses from the command line input (these could range from 1 to X number of email addresses entered) into an array called 'emails'
Save the brand IDs (integers) from the command line input (these could range from 1 to X number of brand IDs entered) into an array called 'brands'
Use nested for loops to iterate over the 'emails' and 'brands' arrays and add each email address to each brand via add.py
I am running into trouble splitting up and saving data into each array, because I do not know where the command line indices of the emails will stop, and where the indices of the brands will begin. Is there any way I can accomplish this?
command line input I expect to look as follows:
me#some-remote-machine:~$ bash script.sh person1#gmail.com person2#gmail.com person3#gmail.com ... personX#gmail.com brand1 brand2 brand3 ... brandX
The contents of script.sh look like this:
#!/bin/bash
cd some/directory
emails= ???
brands= ???
for i in $emails
do
for a in $brands
do
python test.py add --email=$i --brand_id=$a --grant=manage
done
done
Thank you in advance, and please let me know if I can clarify or provide more information.
Use a sentinel argument that cannot possibly be a valid e-mail address. For example:
$ bash script.sh person1#gmail.com person2#gmail.com '***' brand1 brand2 brand3
Then in a loop, you can read arguments until you reach the non-email; everything after that is a brand.
#!/bin/bash
cd some/directory
while [[ $1 != '***' ]]; do
emails+=("$1")
shift
done
shift # Ignore the sentinal
brands=( "$#" ) # What's left
for i in "${emails[#]}"
do
for a in "${brands[#]}"
do
python test.py add --email="$i" --brand_id="$a" --grant=manage
done
done
If you can't modify the arguments that will be passed to script.sh, then perhaps you can distinguish between an address and a brand by the presence or absence of a #:
while [[ $1 = *#* ]]; do
emails+=("$1")
shift
done
brands=("$#")
I'm assuming that the number of addresses and brands are independent. Otherwise, you can simply look at the total number of arguments $#. Say there are N of each. Then
emails=( "${#:1:$#/2}" ) # First half
brands=( "${#:$#/2+1}" ) # Second half