165
votes
Accepted
Replace environment variables in a file with their actual values?
You could use envsubst (part of gnu gettext):
envsubst < infile
will replace the environment variables in your file with their corresponding value. The variable names must consist solely of ...
- 81.4k
54
votes
Replace environment variables in a file with their actual values?
This is not very nice but it works
( echo "cat <<EOF" ; cat config.xml ; echo EOF ) | sh
If it was in a shell script it would look like:
#! /bin/sh
cat <<EOF
<property>
<...
- 2,880
43
votes
Accepted
Extract an attribute value from XML
Use an XML parser for parsing XML data. With xmlstarlet it just becomes an XPath exercise:
$ branch=$(xmlstarlet sel -t -v '//blah1[@name="andy"]/@branch' file.xml)
$ echo $branch
master
- 85.1k
38
votes
Accepted
How to insert variables inside a string containing ""?
You can embed variables only in double-quoted strings.
An easy and safe way to make this work is to break out of the single-quoted string like this:
xml='<?xml version="1.0" encoding="iso-8859-1"?...
- 11.3k
17
votes
Extract an attribute value from XML
With grep:
grep -Pio 'name="andy".*branch="\K[^"]*' file
-P enable perl regular expressions (PCRE)
-i ignore case
-o print only matched parts
In the regex, the \K is a zero-width lookbehind to ...
- 25.3k
17
votes
Extracting sea level pressure from KML using Shell
I suggest to use a tool that can handle XML correctly:
xmlstarlet select --template --value-of '//minSeaLevelPres' -n weatherdata.kml
Output:
1002
See: xmlstarlet select --help
- 12.1k
14
votes
Parse XML to get node value in bash script?
Using xmllint and the --xpath option, it is very easy. You can simply do this:
XML_FILE=/path/to/file.xml
HOST=$(xmllint --xpath 'string(/config/global/resources/default_setup/connection/host)' $...
- 346
14
votes
Replace environment variables in a file with their actual values?
If you happen to have Perl (but not gettext and envsubst) you can do the simple replacement with a short script:
$ export INSTANCE_ID=foo; export SERVICE_NAME=bar;
$ perl -pe 's/\$([_A-Z]+)/$ENV{$1}/...
- 135k
14
votes
Accepted
$1 not working with sed
sed backreferences have the form \1, \2, etc. $1 is more Perl-like. Also, if using basic regular expressions (BRE), you need to escape the parentheses (...) forming a group, as well as ? and +. Or you ...
- 71.3k
14
votes
Accepted
How to remove nodes from XML file as command line with namespace?
TL;DR
please, never ever use sed for this task !
Everytime you use sed for html or xml, you kill a kitty
It's a task for xmlstarlet
(a proper XML parser) and his friend xpath, like this:
xmlstarlet ...
- 32.7k
14
votes
Shell script to remove child xml tags conditionally
Although possible, it is a very, very bad idea to attempt to parse XML or HTML with tools like sed that are based on regular expressions. That can work for simple cases but gets really hard to get ...
- 239k
13
votes
How to insert variables inside a string containing ""?
Variable expansion doesn't happen in single quote strings.
You can use double quotes for your string, and escape the double quotes inside with \. Like this :
xml="<?xml version=\"1.0\" encoding=\"...
- 1,308
13
votes
How to find a specific tag section in an XML file?
Since your given example is a valid XML file, so I would use xq XML parser tool for that which is part of the yq installation package.
xq -x --xml-root key '
.schemalist.schema.key[] | select(.&...
- 41.1k
12
votes
Extract an attribute value from XML
Use xmllint to extract the value of the attribute using XPath:
xmllint --xpath 'string(/blah/blah1[@name="andy"]/@branch)' file.xml
It's better to use an XML parser to process XML since the order of ...
- 308
10
votes
Modify multiple lines of an XML file using command line
Use a proper xmltool, in shell, xmlstarlet is a good one :
xmlstarlet edit -L -u "//Model500[1]" -v "AAA
BBB
CCC" file.xml
...
- 32.7k
10
votes
Accepted
sed on cygwin can only replace one character?
Most probably, that file is encoded in UTF-16, that is with 2 or 4 bytes per characters, probably even with a Byte-Order-Mark at the beginning.
The characters that are shown in your sample (all ASCII ...
- 533k
9
votes
Extract value from XML
Don't use regular expressions to parse XML. Use an XML aware tool, e.g. xmllint:
xmllint --xpath 'string(/results/testsuites/testcase/@time)' file.xml
- 46.4k
9
votes
Extract the Children of a Specific XML Element Type
If you really want sed- or awk-like command-line processing for XML files then you should probably consider using an XML-processing command-line tool. Here are some of the tools that I've seen more ...
- 9,776
9
votes
XML context grepping
If this is part of a well formed XML document you can extract the required part with an XML parser.
To satisfy the well formed requirement, I've wrapped your XML fragment with <root> and </...
- 111k
9
votes
XML command line (shell script) manipulation
XMLStarlet (http://xmlstar.sourceforge.net/overview.php) is written in C and uses libxml2 and libxslt.
Given the XML document
<?xml version="1.0"?>
<root>
<tag>data</tag>
&...
- 327k
9
votes
Accepted
Change XML node's value, using sed?
You would use an XML parser to do this. For example xmlstarlet (a command line XML tool):
$ xmlstarlet ed -u '//client-version' -v '1.2.9' file.xml
<?xml version="1.0"?>
<client-...
- 327k
9
votes
reading XML file and extract only node names and structure
The xmllint interactive shell command du appears to provide what you want:
du PATH
Show the structure of the subtree under the given path or the current node.
If you want something non-...
- 79.7k
8
votes
Accepted
How to fix "cannot find -lxml2" error while installing 'igraph' for python?
libxml2 is the runtime shared library, suitable for running already-compiled programs that use that library. If you want to compile programs that use libxml2, you need to install libxml2-dev.
This ...
- 77.7k
8
votes
how to use patch and diff to merge two files and automatically resolve conflicts
sdiff (1) - side-by-side merge of file differences
Use the --output option, this will interactively merge any two files. You use simple commands to select a change or edit a change.
You should make ...
8
votes
Accepted
XMLstarlet for JSON?
jq provides a rich expression language for selecting elements from a JSON document.
Thus, it is similar to the sel command of xmlstartlet (which takes an XPath expression).
For example, to extract a ...
- 56.8k
8
votes
Fetching the string inside single quote
To extract the value of all file attributes of all source nodes in an XML document, you may use xmlstarlet like this:
xmlstarlet sel -t -v '//source/@file' -nl file.xml
Or, reading from your virsh ...
- 327k
8
votes
How to find a specific tag section in an XML file?
Since you are dealing with valid XML, you can use xmlstarlet:
xmlstarlet sel -t -c "/schemalist/schema/key[@name='enabled']" infile.xml
This will query (sel) the XML document and print a ...
- 22.4k
8
votes
Sorting an XML file in UNIX with a Bash script?
[with a generous assist from Kusalananda]
You can do it using the xq wrapper from yq (a jq wrapper for YAML/XML) to leverage jq's sorting capabilities:
$ xq -x 'getpath([paths(scalars)[0:-1]] | unique ...
- 79.7k
8
votes
Using sed to replace one character with another within an xml tag
Assuming you have some XML document, like
<data>
<episode-num system="onscreen">S1 E12</episode-num>
<episode-num system="onscreen">S1 S12</episode-num&...
- 327k
8
votes
Can I extract complete dates from file with grep command?
Don't use grep nor regex to parse HTML/XML you cannot, must not parse any structured text like XML/HTML with tools designed to process raw text lines. If you need to process XML/HTML, use an XML/HTML ...
- 32.7k
Only top scored, non community-wiki answers of a minimum length are eligible