If you want a variable to reference another variable in Bash, that is possible using a concept called indirect reference. Below is a simple example where ‘varname’ contains the name of another variable ‘foo’. # our variable foo=bar # our reference varname=foo # the following syntax will ERROR and DOES NOT work !!! echo “${$varname}” … Bash: indirect reference to evaluate a variable value
If you have a complex JSON data structure or perhaps an array of rich data structures as the result of module output, you may want to extract this into a workable list or dictionary you can take action on. For this article, I will emulate the resulting output from the ‘stat‘ module when it checks … Ansible: extracting a list or dictionary from a complex data structure
If you have captured the multi-line output of a previous Bash command in a variable and later need to count the number of lines stored in that variable, you may reach for an apparently easy solution first. But there are corner cases you may not have covered. The first syntax gotcha is to make sure … Bash: count number of lines in previously captured stdout
With Ansible, it is possible to have a variable populated with either the content of a remote or local file. For a file on a remote host, you can use the ‘slurp‘ module to put the content into a register, but then you must base64 decode the content. – name: get content of remote file … Ansible: creating a variable from a remote or local file content
It is typically straightforward to resolve Ansible errors where a simple variable used within an action is not defined. However, when dealing with nested dictionary variables in your Ansible tasks, it can become more complex because not only can the leaf be missing, but also any of the parent container paths. For example, the nested … Ansible: pulling values from nested dictionaries when path might not exist
If you are in the middle of a text processing pipeline, and need to insert a shell or environment variable into the output of awk, you can use the “-v” flag. Here are two files containing animal classifications: $ echo -e “shark=fish\ndolphin=mammal” > ocean.txt $ echo -e “dog=mammal\neagle=bird” > land.txt By passing the loop variable … Bash: Using shell or environment variables in awk output
When using jinja2 for SaltStack formulas you may be surprised to find that your global scoped variables do not have ability to be modified inside a loop. Although this is counter intuitive given the scope behavior of most scripting languages it is unfortunately the case that a jinja2 globally scoped variable cannot be modified from … SaltStack: Setting a jinja2 variable from an inner block scope