yamlBash.sh

Bash script to replace a value of a key:value pair in a yaml file while keeping original structure and comments.

(Nested) Key elements should be separated by ":", e.g. Key0:Key1:Key2. Key elements are treated as regex, so can e.g. be specified like "St.*". This will pick up any key starting with "St" and might lead to more than one line being changed.

Currently yamlBash.sh supports only changes to mappings/dictionaries, as e.g.

Key0:
  Key1: Null
  Key2: xxxx
     Key3: to be replaced
  Key4: yyyy
Key5: zzzz

and allows to e.g. replace/insert a value for Key3. Key parameter would be Key0:Key2:Key3.

Current settings/restrictions:

• If the target key has sub-maps (additional lines with higher indent), those will be replaced by the provided value parameter, deleting/replacing those sub-maps. Only comments on the same line a the key will be retained
• A key value provided by the -v parameter has to be a simple scalar or string and will get applied without. any transformation, e.g. required apostrophes etc have to be part of the provided value parameter.
• When using the -f / --file parameter, the following applies:
  • If the file contains a single line (trailing blank lines are ignored), the content of that line will be handeled like a -v parameter.
  • If the file has more than one line, the content will be treated as sub-mapping and the corresponding lines will get inserted as-is (including comments) after the target key, replacing any value/sub-mapping in the original yaml file. Indention of those new lines is adjusted to fit into the original structure as below:
    • Any (starting; line 1) indent in the value file will be removed and replaced by the next level of indent of the target key. This additional indent will be detected in the original file. If nothing can be detected, a default indent (set in the script; usually 2 spaces) will be used.
• Other forms of YAML structures and notations (e.g. lists, block or flow style) will not be changed, but left as-is.
• No support for multi-line strings.

ymf.sh uses stdIn and stdOut to allow piping / redirection to implement multiple changes to a yaml file. Check out the provided example script.

Help for yamlBash.sh:
  Function: Replace value for a (nested) key identified by the "key" parameter in a yaml file
            while keeping structure and comments.

  (Required) Parameters are:
     -k / --key          Key name to be altered as above in the format Level0:Level1:Level2 ....
     -v / --value        (New) value for the key
     -f / --file         File with the (new) value for the key
                         -v or -f have to be provided. -v takes precedence over -f
    Optional:
    -c / --check         File(s) will be checked against the use of tab characters (YAML uses spaces) "
    -h / --help / ?      Help