Shell

XML processing with shell tools. Mainly XMLStarlet, and also xmllint for validation. This refers to the exercises described here.

XMLStarlet is like grep and sed specialized for XML files. It may feel a little complicated at first but it gets easier when you realize that it makes heavy use of XSLT and XPath concepts. In particular, the select operations almost read like an XSLT template.

Exercise 1

Use xmlstarlet's sel (select) operation. Use the -N option to bind a prefix to a namespace, the -t (--template), -m (--match) and -v (--value-of) options like their XSLT counterparts, the -o (--output) option for literal text output and the -n (--nl) option for a newline.

xmlstarlet sel \
    -N 't=http://martin.hoppenheit.info/code/generic-tree-xml' \
    -N 'e=http://purl.org/dc/elements/1.1/' \
    -t -m '//t:node[not(t:node)]/t:content' \
    -v 'e:creator' -o ', ' -v 'e:title' -n \
    ../xml/example.xml

Exercise 2

Use xmlstarlet's sel (select) operation. Use the -N option to bind a prefix to a namespace, the -t (--template), -m (--match) and -v (--value-of) options like their XSLT counterparts, the -o (--output) option for literal text output and the -n (--nl) option for a newline. Use the --if and --else options for conditional constructs. This only searches the parent element, no other ancestors!

xmlstarlet sel \
    -N 't=http://martin.hoppenheit.info/code/generic-tree-xml' \
    -N 'e=http://purl.org/dc/elements/1.1/' \
    -t -m '//t:node[not(t:node)]/t:content' \
    --if 'e:creator' \
        -v 'e:creator' -o ', ' -v 'e:title' -n \
    --else \
        -v '../../t:content/e:creator' -o ', ' -v 'e:title' -n \
    ../xml/example.xml

Exercise 3

Use xmlstarlet's ed (edit) operation. Use the -N option to bind a prefix to a namespace, the -u (--update) option to select the element to be modified and the -x (--expr) option to provide an expression that will be applied to the element's content. The translate operation is an XPath function.

xmlstarlet ed \
    -N 'e=http://purl.org/dc/elements/1.1/' \
    -u '//e:title' \
    -x 'translate(., "abcdefghijklmnopqrstuvwxyz",
                    "ABCDEFGHIJKLMNOPQRSTUVWXYZ")' \
    ../xml/example.xml

Exercise 4

TODO

Exercise 5

Use xmlstarlet's ed (edit) operation. Use the -N option to bind a prefix to a namespace and the -d (--delete) option to select the element to be deleted.

xmlstarlet ed \
    -N 't=http://martin.hoppenheit.info/code/generic-tree-xml' \
    -d '//t:node[@name="Programming Books"]' \
    ../xml/example.xml

Exercise 6

Use xmlstarlet's val (validate) operation. Use the -s (--xsd) option to provide an XML schema file.

xmlstarlet val -s ../xml/gtr_dc.xsd ../xml/example.xml

Instead of xmlstarlet, xmllint can be used. Use the --noout option to suppress output of the validated XML file and the --schema option to provide and XML schema file. If you want to see which additional schema files are fetched because they are referenced in the provided schema file, add the --load-trace option.

xmllint --noout --schema ../xml/gtr_dc.xsd ../xml/example.xml