I have a sample json response as shown below which i am trying to parse using jq in shell script.[{"id":1,"notes":"Demo1\nDemo2"}]
This is the command through which I am trying to access notes in the shell script.
value=($(curl $URL | jq -r '.[].notes'))
When I echo "$value" I only get Demo1. How to get the exact value: Demo1\nDemo2 ?
To clarify, there is no backslash or n in the notes field. \n is JSON's way of encoding a literal linefeed, so the value you should be expecting is:
Demo1
Demo2
The issue you're seeing is because you have split the value on whitespace and created an array. Each value can be accessed by index:
$ cat myscript
data='[{"id":1,"notes":"Demo1\nDemo2"}]'
value=($(printf '%s' "$data" | jq -r '.[].notes'))
echo "The first value was ${value[0]} and the second ${value[1]}"
$ bash myscript
The first value was Demo1 and the second Demo2
To instead get it as a simple string, remove the parens from value=(..):
$ cat myscript2
data='[{"id":1,"notes":"Demo1\nDemo2"}]'
value=$(printf '%s' "$data" | jq -r '.[].notes')
echo "$value"
$ bash myscript2
Demo1
Demo2
Related
I'm using groovy script and write this line
Version_List=$(jq -r '.items[] .version' "${projectContent}")
the ${projectContent} is another variable which is result of curl command
when i run the pipeline this is the error /bin/jq: Argument list too long
Use jq -Rs . <<< "${projectContent}" to convert the variable content into a JSON string (you may even use curl directly, like so: curl … | jq -Rs), then import that string into a jq variable using --slurpfile with Process Substitution
jq --slurpfile projectContent <(
jq -Rs . <<< "${projectContent}"
) '...' # your jq code here using variable $projectContent
Don't forget to also add either -n or an input file.
I parsed a json file with jq like this :
# cat test.json | jq '.logs' | jq '.[]' | jq '._id' | jq -s
It returns an array like this : [34,235,436,546,.....]
Using bash script i described an array :
# declare -a msgIds = ...
This array uses () instead of [] so when I pass the array given above to this array it won't work.
([324,32,45..]) this causes problem. If i remove the jq -s, an array forms with only 1 member in it.
Is there a way to solve this issue?
We can solve this problem by two ways. They are:
Input string:
// test.json
{
"keys": ["key1","key2","key3"]
}
Approach 1:
1) Use jq -r (output raw strings, not JSON texts) .
KEYS=$(jq -r '.keys' test.json)
echo $KEYS
# Output: [ "key1", "key2", "key3" ]
2) Use #sh (Converts input string to a series of space-separated strings). It removes square brackets[], comma(,) from the string.
KEYS=$(<test.json jq -r '.keys | #sh')
echo $KEYS
# Output: 'key1' 'key2' 'key3'
3) Using tr to remove single quotes from the string output. To delete specific characters use the -d option in tr.
KEYS=$((<test.json jq -r '.keys | #sh')| tr -d \')
echo $KEYS
# Output: key1 key2 key3
4) We can convert the comma-separated string to the array by placing our string output in a round bracket().
It also called compound Assignment, where we declare the array with a bunch of values.
ARRAYNAME=(value1 value2 .... valueN)
#!/bin/bash
KEYS=($((<test.json jq -r '.keys | #sh') | tr -d \'\"))
echo "Array size: " ${#KEYS[#]}
echo "Array elements: "${KEYS[#]}
# Output:
# Array size: 3
# Array elements: key1 key2 key3
Approach 2:
1) Use jq -r to get the string output, then use tr to delete characters like square brackets, double quotes and comma.
#!/bin/bash
KEYS=$(jq -r '.keys' test.json | tr -d '[],"')
echo $KEYS
# Output: key1 key2 key3
2) Then we can convert the comma-separated string to the array by placing our string output in a round bracket().
#!/bin/bash
KEYS=($(jq -r '.keys' test.json | tr -d '[]," '))
echo "Array size: " ${#KEYS[#]}
echo "Array elements: "${KEYS[#]}
# Output:
# Array size: 3
# Array elements: key1 key2 key3
To correctly parse values that have spaces, newlines (or any other arbitrary characters) just use jq's #sh filter and bash's declare -a. (No need for a while read loop or any other pre-processing)
// foo.json
{"data": ["A B", "C'D", ""]}
str=$(jq -r '.data | #sh' foo.json)
declare -a arr="($str)" # must be quoted like this
$ declare -p arr
declare -a arr=([0]="A B" [1]="C'D" [2]="")
The reason that this works correctly is that #sh will produce a space-separated list of shell-quoted words:
$ echo "$str"
'A B' 'C'\''D' ''
and this is exactly the format that declare expects for an array definition.
Use jq -r to output a string "raw", without JSON formatting, and use the #sh formatter to format your results as a string for shell consumption. Per the jq docs:
#sh:
The input is escaped suitable for use in a command-line for a POSIX shell. If the input is an array, the output will be a series of space-separated strings.
So can do e.g.
msgids=($(<test.json jq -r '.logs[]._id | #sh'))
and get the result you want.
From the jq FAQ (https://github.com/stedolan/jq/wiki/FAQ):
𝑸: How can a stream of JSON texts produced by jq be converted into a bash array of corresponding values?
A: One option would be to use mapfile (aka readarray), for example:
mapfile -t array <<< $(jq -c '.[]' input.json)
An alternative that might be indicative of what to do in other shells is to use read -r within a while loop. The following bash script populates an array, x, with JSON texts. The key points are the use of the -c option, and the use of the bash idiom while read -r value; do ... done < <(jq .......):
#!/bin/bash
x=()
while read -r value
do
x+=("$value")
done < <(jq -c '.[]' input.json)
++ To resolve this, we can use a very simple approach:
++ Since I am not aware of you input file, I am creating a file input.json with the following contents:
input.json:
{
"keys": ["key1","key2","key3"]
}
++ Use jq to get the value from the above file input.json:
Command: cat input.json | jq -r '.keys | #sh'
Output: 'key1' 'key2' 'key3'
Explanation: | #sh removes [ and "
++ To remove ' ' as well we use tr
command: cat input.json | jq -r '.keys | #sh' | tr -d \'
Explanation: use tr delete -d to remove '
++ To store this in a bash array we use () with `` and print it:
command:
KEYS=(`cat input.json | jq -r '.keys | #sh' | tr -d \'`)
To print all the entries of the array: echo "${KEYS[*]}"
I have a file with this kind of text with pattern
[{"foo":"bar:baz:foo*","bar*":"baz*","etc":"etc"},
{"foo2":"bar2:baz2:foo2*","bar2*":"baz2*","etc":"etc"},
{"foo3":"bar3:baz3:foo3*","bar3*":"baz3*","etc":"etc"},
{"foo4":"bar4:baz4:foo4*","bar4*":"baz4*","etc":"etc"}]
I need to take every string like this
{"foo":"bar:baz:foo*","bar*":"baz*","etc":"etc"} and send each of them to some url via curl
for i in text.txt
do (awk,sed,grep etc)
then curl $string
I can't figure out how to get the desired lines properly from the file without unnecessary symbols
I suggest that you can use jq to process your json file. jq is capable of reading json, and formatting output. Here's an example jq script to process your json file (which I unimaginatively call 'jsonfile'):
jq -r '.[] | "curl -d '\'' \(.) '\'' http://restful.com/api " ' jsonfile
Here's the output:
curl -d ' {"foo":"bar:baz:foo*","bar*":"baz*","etc":"etc"} ' http://restful.com/api
curl -d ' {"foo2":"bar2:baz2:foo2*","bar2*":"baz2*","etc":"etc"} ' http://restful.com/api
curl -d ' {"foo3":"bar3:baz3:foo3*","bar3*":"baz3*","etc":"etc"} ' http://restful.com/api
curl -d ' {"foo4":"bar4:baz4:foo4*","bar4*":"baz4*","etc":"etc"} ' http://restful.com/api
Here's what's going on:
We pass three arguments to the jq program: jq -r <script> <inputfile>.
The -r tells jq to output the results in raw format (that is, please don't escape quotes and stuff).
The script looks like this:
.[] | "some string \(.)"
The first . means take the whole json structure and the [] means iterate through each array element in the structure. The | is a filter that processes each element in the array. The filter is to output a string. We are using \(.) to interpolate the whole element passed into the | filter.
Wow... I've never really explained a jq script before (and it shows). But the crux of it is, we are using jq to find each element in the json array and insert it into a string. Our string is this:
curl -d '<the json dictionary array element>' http://restful.com/api
Ok. And you see the output. It works. But wait a second, we only have output. Let's tell the shell to run each line like this:
jq -r '.[] | "curl -d '\'' \(.) '\'' http://restful.com/api " ' jsonfile | bash
By piping the output to bash, we execute each line that we output. Essentially, we are writing a bash script with jq to curl http://restful.com/api passing the json element as the -d data parameter to POST the json element.
Revisiting for single quote issue
#oguz ismail pointed out that bash will explode if there is a single quote in the json input file. This is true. We can avoid the quote by escaping, but we gain more complexity - making this a non-ideal approach.
Here's the problem input (I just inserted a single quote):
[{"foo":"bar:'baz:foo*","bar*":"baz*","etc":"etc"},
{"foo2":"bar2:baz2:foo2*","bar2*":"baz2*","etc":"etc"},
{"foo3":"bar3:baz3:foo3*","bar3*":"baz3*","etc":"etc"},
{"foo4":"bar4:baz4:foo4*","bar4*":"baz4*","etc":"etc"}]
Notice above that baz is now 'baz. The problem is that a single single quote makes the bash shell complain about unmatched quotes:
$ jq -r '.[] | "curl -d '\'' \(.) '\'' http://restful.com/api " ' jsonfile | bash
bash: line 4: unexpected EOF while looking for matching `"'
bash: line 5: syntax error: unexpected end of file
Here's the solution:
$ jq -r $'.[] | "\(.)" | gsub( "\'" ; "\\\\\'" ) | "echo $\'\(.)\'" ' jsonfile | bash
{"foo":"bar'baz:foo*","bar*":"baz*","etc":"etc"}
{"foo2":"bar2:baz2:foo2*","bar2*":"baz2*","etc":"etc"}
{"foo3":"bar3:baz3:foo3*","bar3*":"baz3*","etc":"etc"}
{"foo4":"bar4:baz4:foo4*","bar4*":"baz4*","etc":"etc"}
Above I am using $'' to quote the jq script. This allows me to escape single quotes using '. I've also changed the curl command to echo so I can test the bash script without bothering the folks at http://restful.com/api.
The 'trick' is to make sure that the bash script we generate also escapes all single quotes with a backslash . So, we have to change ' to \'. That's what gsub is doing.
gsub( "\'" ; "\\\\\'" )
After making that substitution ( ' --> \' ) we pipe the entire string to this:
"echo $\'\(.)\'"
which surrounds the output of gsub with echo $''. Now we are using $' again so the \' is properly understood by bash.
So we wind up with this when we put the curl back in:
jq -r $'.[] | "\(.)" | gsub( "\'" ; "\\\\\'" ) | "curl -d $\'\(.)\' http://restful.com/api " ' jsonfile | bash
Use jq command. This is just example parsing.
for k in $(jq -c '.[]' a.txt); do
echo "hello-" $k
done
Output:
hello- {"foo":"bar:baz:foo*","bar*":"baz*","etc":"etc"}
hello- {"foo2":"bar2:baz2:foo2*","bar2*":"baz2*","etc":"etc"}
hello- {"foo3":"bar3:baz3:foo3*","bar3*":"baz3*","etc":"etc"}
hello- {"foo4":"bar4:baz4:foo4*","bar4*":"baz4*","etc":"etc"}
You can use the $k anywhere inside the loop you want.
for k in $(jq -c '.[]' a.txt); do
curl -d "$k" <url>
done
I have a first json file like this:
{
"env_vars": {
"TERRAFORM_CFG_TLS_CERT": "-----BEGIN CERTIFICATE----\\nMIIIqzCCB5O"
}
}
If I use the command:
echo <file> | jq -r '.env_vars'
The result is as expected (the backslash are still there):
{
"TERRAFORM_CFG_TLS_CERT": "-----BEGIN CERTIFICATE----\\nMIIIqzCCB5O"
}
But if i execute this command:
cat <file> | jq -r '.env_vars' | jq -r 'keys[] as $k | "\($k)=\"\(.[$k])\""'
The result is:
TERRAFORM_CFG_TLS_CERT: "-----BEGIN CERTIFICATE----\nMIIIqzCCB5O"
=> One backslash has been removed... why ?
How to avoid this ?
Thanks.
Using the -r option tells jq to "translate" the JSON string into a "raw" string by interpreting the characters that are special to JSON (see e.g. http://json.org). Thus, following the [mcve] guidelines a bit more closely, we could start with:
$ jq . <<< '"X\\nY"'
"X\\nY"
$ jq -r . <<< '"X\\nY"'
X\nY
If you check the json.org specification of strings, you'll see this is exactly correct.
So if for some reason you want each occurrence of \\ in the JSON string to be replaced by two backslash characters (i.e. JSON: "\\\\"), you could use sub or gsub. That's a bit tricky, because the first argument of these functions is a regex. Behold:
$ jq -r 'gsub("\\\\"; "\\\\")' <<< '"X\\nY"'
X\\nY
You should output the string as json to preserve the escapes. By taking a string and outputting it raw, you're getting exactly what that string was, a literal backslash followed by an n.
$ ... | jq -r '.env_vars | to_entries[] | "\(.key): \(.value | tojson)"'
If any of the values are non-strings, add a tostring to the filter.
I have a json file names test.json with the below content.
{
"run_list": ["recipe[cookbook-ics-op::setup_server]"],
"props": {
"install_home": "/test/inst1",
"tmp_dir": "/test/inst1/tmp",
"user": "tuser
}
}
I want to read this file into a variable in shell script & then extract the values of install_home,user & tmp_dir using expr. Can someone help, please?
props=cat test.json
works to get the json file into a variable. Now how can I extract the values using expr. Any help would be greatly appreciated.
Install jq
yum -y install epel-release
yum -y install jq
Get the values in the following way
install_home=$(cat test.json | jq -r '.props.install_home')
tmp_dir=$(cat test.json | jq -r '.props.tmp_dir')
user=$(cat test.json | jq -r '.props.user')
For a pure bash solution I suggest this:
github.com/dominictarr/JSON.sh
It could be used like this:
./json.sh -l -p < example.json
print output like:
["name"] "JSON.sh"
["version"] "0.2.1"
["description"] "JSON parser written in bash"
["homepage"] "http://github.com/dominictarr/JSON.sh"
["repository","type"] "git"
["repository","url"] "https://github.com/dominictarr/JSON.sh.git"
["bin","JSON.sh"] "./JSON.sh"
["author"] "Dominic Tarr <dominic.tarr#gmail.com> (http://bit.ly/dominictarr)"
["scripts","test"] "./all-tests.sh"
From here is pretty trivial achive what you are looking for
jq is a dedicated parser for JSON files. Install jq.
values in the json can be retrieved as:
jq .<top-level-attr>.<next-level-attr> <json-file-path>
if JSON contains an array
jq .<top-level-attr>.<next-level-array>[].<elem-in-array> <json-file-path>
if you want a value in a shell variable
id = $(jq -r .<top-level-attr>.<next-level-array>[].<next-level-attr> <json-file-path>)
echo id
use -r if you need unquoted value
For simple JSON, it may be treated as a plain text file.
In that case, we can use simple text pattern matching to extract the information we need.
If you observe the following lines:
"install_home": "/test/inst1",
"tmp_dir": "/test/inst1/tmp",
"user": "user"
There exists a pattern on each line that can be described as key and value:
"key" : "value"
We can use perl with regular expressions to exact the value for any given key:
"key" hardcoded for each case "install_home", "tmp_dir" and "user"
"value" as (.*) regular expression
Then we use the $1 matching group to retrieve the value.
i=$(perl -ne 'if (/"install_home": "(.*)"/) { print $1 . "\n" }' test.json)
t=$(perl -ne 'if (/"tmp_dir": "(.*)"/) { print $1 . "\n" }' test.json)
u=$(perl -ne 'if (/"user": "(.*)"/) { print $1 . "\n" }' test.json)
cat <<EOF
install_home: $i
tmp_dir : $t
user : $u
EOF
Which outputs:
install_home: /test/inst1
tmp_dir : /test/inst1/tmp
user : tuser