I have a var which can has single quotes or spaces before and/or after:
var="' /path/to/somewhere '"
var=" /path/to/somewhere "#<- here is a space at the end
var="/path/to/somewhere'"
var=" /path/to/somewhere '"
I need a regexp using bash rematch to clean possible single quotes or blank spaces before and after
I know it can be done in this way:
var=${var##+([ \'])}
var=${var%%+([ \'])}
But I need it with BASH_REMATCH (long to explain xd). I'm trying with:
[[ ${var} =~ ^([\' ]*)?(.+)([\' ])?$ ]] && var="${BASH_REMATCH[1]}"
But it doesn't work. Probably .+ is getting the rest of the string. How can I get only the interesting part? Thanks.
The .+ in your example is what's causing the problem, as it is greedy, so it will consume the rest of the line.
In this case, you can prevent it from doing so by requiring that the part in the middle ends in something other than a space or ', like this:
re='^[ '"'"']*(.*[^ '"'"'])[ '"'"']*$'
[[ $var =~ $re ]] && echo "${BASH_REMATCH[1]}"
The nasty-looking '"'"' are needed to insert a literal ' into a single-quoted string. When working with regular expressions in bash, the recommended method is to define a variable containing the pattern in single quotes and then to use it, unquoted (this method works in all versions of bash that support regular expressions).
Related
Inside of my $foo variable I have this data (please pay close attention to the .s and ,s):
,example.com,de.wikipedia.org,reddit,stackoverflow.com.,amazon.,
I am trying to write an if statement in bash that basically works like this:
if [[ "${foo}" =~ *','[a-z0-9]','* || "${foo}" =~ *','[a-z0-9]'.,'* ]]; then
echo "Invalid input detected"
else
echo "OK"
fi
It would echo Invalid input detected since reddit and amazon. are in $foo.
If I change the contents of $foo to be:
,example.com,de.wikipedia.org,www.reddit.com,stackoverflow.com.,amazon.com,
Then it would echo OK.
I am using bash 3.2.57(1)-release on OS X 10.11.6 El Capitan.
Try:
if [[ $foo =~ ,[a-z0-9]*, || $foo =~ ,[a-z0-9]*\., ]]; then
echo "Invalid input detected"
else
echo "OK"
fi
Notes:
=~ is a regular expression operator. The right-hand-side needs to be a regular expression, not a glob.
, is not a shell-active character. Thus, it does not need any special quoting.
[a-z0-9] matches exactly one alphanumeric. Since we want to allow for more any number, use [a-z0-9]*
In regular expressions, ','* matches zero or more commas. This is not what you want. One might write ,.* which, because, . is a wildcard, matches a comma followed by zero or more of anything. Since the regex is not anchored to the end, adding a final .* makes no difference.
Inside of [[...]] there is no word splitting. So shell variables do not the double-quoting that need elsewhere.
Note that, in [a-z0-9], the exact characters that match a-z or 0-9 depend on the collation order in the locale.
I created this regular expression and tested it out successfully
https://regex101.com/r/a7qvuw/1
However the regular expression behaves differently in this bash code that I wrote
# Splitting by colon
IFS=';' read -ra statements <<< $contents
# Splitting by the = sign.
regex="\s*(.*?)\s*=\s*(.*)\b"
for i in "${statements[#]}"; do
if [[ $i =~ $regex ]]; then
key=${BASH_REMATCH[1]}
params=${BASH_REMATCH[2]}
echo "KEY: $key| PARAMS: $params"
fi
done
The variable $contents has the text as is used in the link. The problem is that the $key has a space at its end, while the regular expression I tried matches the words without the space.
I get output like this:
KEY: vclock_spec | PARAMS: clk_i 1 1
As you can see there is a space between vclock_spec and the | which should not be there. What am I doing wrong?
As #Cyrus mentioned, lazy quantifiers are not supported in Bash regex. They act as greedy ones.
You may fix your pattern to work in Bash using
regex="\s*([^=]*\S)\s*=\s*(.*)\b"
^^^^^^^
The [^=]* matches zero or more symbols other then = and \S matches any non-whitespace (maybe [^\s=] will be more precise here as it matches any char but a whitespace (\s) and =, but it looks like regex="\s*([^=]*[^\s=])\s*=\s*(.*)\b" yields the same results).
I am writing a script and I want to check a variable for a format. This is the function I use :
check_non_numeric() {
#re='^\".*\"$'
re='\[^\]*\'
if ! [[ $1 =~ $re ]] ; then
echo "'$1' is not a valid format - \"[name]\" "
exit 1
fi
}
I want the regular expression to match a string with anything but quotation mark inside and quotation marks around it ("a" or "string" or "dsfo!^$**#"). The problem is that these regular expressions that I came up with dont work for me. I have used a very similar function to check if a variable is an integer or float and it worked there. Could you please tell me what the regular expression in question should be ?
Thank you very much
I'm assuming you meant you want to match anything that is not a string surrounded by quotes. It's easier to match use your regex to match, and the bash-test to "not" match it-- if that's not clear, use !. Here's a couple of ways to do it.
if [[ ! $(expr "$string" : '\".*\"') -gt 0 ]]; then echo "expr good"; fi
if [[ ! "$string" =~ \".*\" ]]; then echo "test good"; fi
Make sure you quote your variable you are testing with expr (which is there for edification purposes only).
As you want to match anything except string with quotation marks, you just target the quotation mark:
re='["]'
if [[ ! $1 =~ $re ]] ; then
Actually you don't need regex for this. Globbing will be enough:
if [[ ! $1 = *\"* ]]; then
...
fi
Your regex is very, very far off. \[ matches a literal left square bracket, and ^ (outside a character class) matches beginning of line.
Something like '^"[^"]*"' should work, if that's really what you want.
However, I kind of doubt that. In order to pass a value in literal double quotes, you would need something like
yourprogram '"value"'
or
yourprogram "\"value\""
which I would certainly want to avoid if I were you.
i have some regex that is behaving oddly in my shell script i have variables, and i have tried every what way to get them to behave, and they dont seem to do any regex, and i know my regex quite well thanks to regex101, here is what a sample looks like
fname="direcheck"
FIND="*"
if [[ $fname =~ $FIND ]]; then
echo "no quotes"
fi
if [[ "$fname" =~ "$FIND" ]]; then
echo "with quotes"
fi
right now it will display nothing
if i change find to
FIND="[9]*"
then it prints no quotes
if i say
FIND="[a-z]*"
then it prints no quotes
if i say
FIND="dircheck"
then nothing prints
if i say
FIND="*ck"
then nothing prints
I don't get how this regex is working
how do i use these variables, and what is the proper syntax?
* and *ck are invalid regular expressions. It would work (with no quotes) if you were comparing with ==, not =~. If you want to use the same functionality that you get in == for them, the equivalent regexps are .* and .*ck.
[9]* is any number (including zero) of characters that are 9. There is zero characters 9 in your direcheck, so it matches. (Edited from brainfart, thanks chepner)
dircheck is not found in direcheck, so not printing anything is hardly surprising.
[a-z]* is any number of characters that are between a and z (i.e. any number of lowercase letters). This will match, assuming it's not quoted.
I finally figured it out, and why it was working so oddly
[a-z]* and [9]* and [anythinghere]* they all match because it matches zero or more times. so "direcheck" has [9] zero or more times.
so
if [[ "$fname" =~ $FIND ]]; then
or
if [[ $fname =~ $FIND ]]; then
are both correct, and
if [[ "$fname" =~ "$FIND" ]]; then
matches only when the string matches exactly because $FIND is matched as a literal string not regex
I want to parse strings similar to the following into separate variables using regular expressions from within Bash:
Category: entity;scheme="http://schemas.ogf.org/occi/core#";class="kind";title="Entity";attributes="occi.core.id occi.core.title";
or
Category: resource;scheme="http://schemas.ogf.org/occi/core#";class="kind";title="Resource";rel="http://schemas.ogf.org/occi/core#entity";attributes="occi.core.summary";
The first part before "title" is common to all strings, the parts title and attributes are optional.
I managed to extract the mandatory parameters common to all strings, but I have trouble with optional parameters not necessarily present for all strings. As far as I found out, Bash doesn't support Non-capturing parentheses which I would use for this purpose.
Here is what I achieved thus far:
CATEGORY_REGEX='Category:\s*([^;]*);scheme="([^"]*)";class="([^"]*)";'
category_string='Category: entity;scheme="http://schemas.ogf.org/occi/core#";class="kind";title="Entity";attributes="occi.core.id occi.core.title";'
[[ $category_string =~ $CATEGORY_REGEX ]]
echo ${BASH_REMATCH[0]}
echo ${BASH_REMATCH[1]}
echo ${BASH_REMATCH[2]}
echo ${BASH_REMATCH[3]}
The regular expression I would like to use (and which is working for me in Ruby) would be:
CATEGORY_REGEX='Category:\s*([^;]*);\s*scheme="([^"]*)";\s*class="([^"]*)";\s*(?:title="([^"]*)";)?\s*(?:rel="([^"]*)";)?\s*(?:location="([^"]*)";)?\s*(?:attributes="([^"]*)";)?\s*(?:actions="([^"]*)";)?'
Is there any other solution to parse the string with command line tools without having to fall back on perl, python or ruby?
I don't think non-capturing groups exist in bash regex, so your options are to use a scripting language or to remove the ?: from all of the (?:...) groups and just be careful about which groups you reference, for example:
CATEGORY_REGEX='Category:\s*([^;]*);\s*scheme="([^"]*)";\s*class="([^"]*)";\s*(title="([^"]*)";)?\s*(rel="([^"]*)";)?\s*(location="([^"]*)";)?\s*(attributes="([^"]*)";)?\s*(actions="([^"]*)";)?'
category_string='Category: entity;scheme="http://schemas.ogf.org/occi/core#";class="kind";title="Entity";attributes="occi.core.id occi.core.title";'
[[ $category_string =~ $CATEGORY_REGEX ]]
echo "full: ${BASH_REMATCH[0]}"
echo "category: ${BASH_REMATCH[1]}"
echo "scheme: ${BASH_REMATCH[2]}"
echo "class: ${BASH_REMATCH[3]}"
echo "title: ${BASH_REMATCH[5]}"
echo "rel: ${BASH_REMATCH[7]}"
echo "location: ${BASH_REMATCH[9]}"
echo "attributes: ${BASH_REMATCH[11]}"
echo "actions: ${BASH_REMATCH[13]}"
Note that starting with the optional parameters we need to skip a group each time, because the even numbered groups from 4 on contain the parameter name as well as the value (if the parameter is present).
You can emulate non-matching groups in bash using a little bit of regexp magic:
_2__ _4__ _5__
[[ "fu#k" =~ ((.+)#|)((.+)/|)(.+) ]];
echo "${BASH_REMATCH[2]:--} ${BASH_REMATCH[4]:--} ${BASH_REMATCH[5]:--}"
# Output: fu - k
Characters # and / are parts of string we parse.
Regexp pipe | is used for either left or right (empty) part matching.
For curious, ${VAR:-<default value>} is variable expansion with default value in case $VAR is empty.