I am trying to add quotes to a string. Like this:
stackoverflow => 'stackoverflow'
And then append this string to another variable separated by a 'comma'. like:
${list} (before appending) => 'stackexchange',.....,'meta'
${list},'stackoverflow' => 'stackexchange',.....,'meta','stackoverflow'
I've tried to do this:
if [ -z "$partition_list" ]
then
partition_list="'"${partition}"'"
else
partition_list=${partition_list}",'"${partition}"'"
fi
Note: $partition is the variable that I am trying to add quotes to. And $partition_list is the list I am trying to append $partition to.
It didn't work. I get the strings like this: ''\''10099'\''
EDIT:
I am getting the value of partition through this statement:
partition=`echo $f | awk -F '=' '{print $2}'`
Is there a way we can add 'sed' to this statement and add the quotes to $partition?
Any help would be much appreciated.
Thank you.
What about just this?
partition_list="${partition_list:+$partition_list,}'$partition'"
The if construct is replaced with parameter expansion that includes the comma if $partition_list is not null (using :+), and the single quotes inside double quotes don't stop the variable from being expanded.
Plus ... always quote the variables you refer to. Your idea of foo=$bar",'"$baz"'" has the potential to be disastrous because the variables might be expanded through globbing.
So if you DID want to do this with the if, it would look more like:
if [ -z "$partition_list" ]; then
partition_list="'${partition}'"
else
partition_list="${partition_list},'${partition}'"
fi
How about:
//EDIT: updated for handling spaces.
list=('aa xx' 'bb')
res=()
for ix in ${!list[*]};do
res+=(\'${list[$ix]}\')
done
res+=("'stackoverflow'")
echo ${res[*]}
Related
I have two strings saved in a bash variable delimited by :. I want to get extract the second string, prepend that with THIS_VAR= and append it to a file named saved.txt
For example if myVar="abc:pqr", THIS_VAR=pqr should be appended to saved.txt.
This is what I have so far,
myVar="abc:pqr"
echo $myVar | cut -d ':' -f 2 >> saved.txt
How do I prepend THIS_VAR=?
printf 'THIS_VAR=%q\n' "${myVar#*:}"
See Shell Parameter Expansion and run help printf.
The more general solution in addition to #konsolebox's answer is piping into a compound statement, where you can perform arbitrary operations:
echo This is in the middle | {
echo This is first
cat
echo This is last
}
I have key value pairs in a string like this:
key1 = "value1"
key2 = "value2"
key3 = "value3"
In a bash script, I need to extract the value of one of the keys like for key2, I should get value2, not in quote.
My bash script needs to work in both Redhat and Ubuntu Linux hosts.
What would be the easiest and most reliable way of doing this?
I tried something like this simplified script:
pattern='key2\s*=\s*\"(.*?)\".*$'
if [[ "$content" =~ $pattern ]]
then
key2="${BASH_REMATCH[1]}"
echo "key2: $key2"
else
echo 'not found'
fi
But it does not work consistently.
Any better/easier/more reliable way of doing this?
To separate the key and value from your $content variable, you can use:
[[ $content =~ (^[^ ]+)[[:blank:]]*=[[:blank:]]*[[:punct:]](.*)[[:punct:]]$ ]]
That will properly populate the BASH_REMATCH array with both values where your key is in BASH_REMATCH[1] and the value in BASH_REMATCH[2].
Explanation
In bash the [[...]] treats what appears on the right side of =~ as an extended regular expression and matched according to man 3 regex. See man 1 bash under the section heading for [[ expression ]] (4th paragraph). Sub-expressions in parenthesis (..) are saved in the array variable BASH_REMATCH with BASH_REMATCH[0] containing the entire portion of the string (your $content) and each remaining elements containing the sub-expressions enclosed in (..) in the order the parenthesis appear in the regex.
The Regular Expression (^[^ ]+)[[:blank:]]*=[[:blank:]]*[[:punct:]](.*)[[:punct:]]$ is explained as:
(^[^ ]+) - '^' anchored at the beginning of the line, [^ ]+ match one or more characters that are not a space. Since this sub-expression is enclosed in (..) it will be saved as BASH_REMATCH[1], followed by;
[[:blank:]]* - zero or more whitespace characters, followed by;
= - an equal sign, followed by;
[[:blank:]]* - zero or more whitespace characters, followed by;
[[:punct:]] - a punctuation character (matching the '"', which avoids caveats associated with using quotes within the regex), followed by the sub-expression;
(.*) - zero or more characters (the rest of the characters), and since it is a sub-expression in (..) it the characters will be stored in BASH_REMATCH[2], followed by;
[[:punct:]] - a punctuation character (matching the '"' ... ditto), at the;
$ - end of line anchor.
So if you match what your key and value input lines separated by an = sign, it will separate the key and value into the array BASH_REMATCH as you wanted.
Bash supports BRE only and you cannot use \s and .*?.
As an alternative, please try:
while IFS= read -r content; do
# pattern='key2\s*=\s*\"(.*)\".*$'
pattern='key2[[:blank:]]*=[[:blank:]]*"([^"]*)"'
if [[ $content =~ $pattern ]]
then
key2="${BASH_REMATCH[1]}"
echo "key2: $key2"
(( found++ ))
fi
done < input-file.txt
if (( found == 0 )); then
echo "not found"
fi
What you start talking about key-value pairs, it is best to use an associative array:
declare -A map
Now looking at your lines, they look like key = "value" where we assume that:
value is always encapsulated by double quotes, but also could contain a quote
an unknown number of white spaces is before and/or after the equal sign.
So assuming we have a variable line which contains key = "value", the following operations will extract that value:
key="${line%%=*}"; key="${key// /}"
value="${line#*=}"; value="${value#*\042}"; value="${value%\042*}"
IFS=" \t=" read -r value _ <<<"$line"
This allows us now to have something like:
declare -A map
while read -r line; do
key="${line%%=*}"; key="${key// /}"
value="${line#*=}"; value="${value#*\042}"; value="${value%\042*}"
map["$key"]="$value"
done <inputfile
With awk:
awk -v key="key2" '$1 == key { gsub("\"","",$3);print $3 }' <<< "$string"
Reading the output of the variable called string, pass the required key in as a variable called key and then if the first space delimited field is equal to the key, remove the quotes from the third field with the gsub function and print.
Ok, after spending so many hours, this is how I solved the problem:
If you don't know where your script will run and what type of file (win/mac/linux) are you reading:
Try to avoid non-greedy macth in linux bash instead of tweaking diffrent switches.
don't trus end of line match $ when you might get data from windows or mac
This post solved my problem: Non greedy text matching and extrapolating in bash
This pattern works for me in may linux environments and all type of end of lines:
pattern='key2\s*=\s*"([^"]*)"'
The value is in BASH_REMATCH[1]
I'm writing a for loop in bash to run a command and I need to add a comma after one of my variables. I can't seem to do this without an extra space added. When I move "," right next to $bams then it outputs *.sorted,
#!/bin/bash
bams=*.sorted
for i in $bams
do echo $bams ","
done;
Output should be this:
'file1.sorted','file2.sorted','file3.sorted'
The eventual end goal is to be able to insert a list of files into a --flag in the format above. Not sure how to do that either.
First, a literal answer (if your goal were to generate a string of the form 'foo','bar','baz', rather than to run a program with a command line equivalent to somecommand --flag='foo','bar','baz', which is quite different):
shopt -s nullglob # generate a null result if no matches exist
printf -v var "'%s'," *.sorted # put list of files, each w/ a comma, in var
echo "${var%,}" # echo contents of var, with last comma removed
Or, if you don't need the literal single quotes (and if you're passing your result to another program on its command line with the single quotes being syntactic rather than literal, you absolutely don't want them):
files=( *.sorted ) # put *.sorted in an array
IFS=, # set the comma character as the field separator
somecommand --flag "${files[*]}" # run your program with the comma-separated list
try this -
lst=$( echo *.sorted | sed 's/ /,/g' ) # stack filenames with commas
echo $lst
if you really need the single-ticks around each filename, then
lst="'$( echo *.sorted | sed "s/ /','/g" )'" # commas AND quotes
#!/bin/bash
bams=*.sorted
for i in $bams
do flag+="${flag:+,}'$i'"
done
echo $flag
Someone please help to explain how this work? About the single quote it should not interpret anything but it is not working as what i expected. I expect to get echo $testvar value exactly '"123b"'.
a="testvar"
b="'"123b"'"
eval $a='$b'
echo $testvar
'123b'
a="testvar"
b='"123b"'
eval $a='$b'
echo $testvar
"123b"
a="testvar"
b='"123b"'
eval $a=$b
echo $testvar
123b
Guessing that you want testvar to be <single-quote><double-quote>123b<double-quote><single-quote>:
testvar=\'\"123b\"\'
Consider this in C or Java:
char* str = "123b";
printf("%s\n", str);
String str = "123b";
System.out.println(str);
Why does this write 123b when we clearly used double quotes? Why doesn't it write "123b", with quotes?
The answer is that the quotes are not part of the data. The quotes are used by the programming language to determine where strings start and stop, but they're not in any way part of the string. This is just as true for Bash as for C and Java.
Just like there's no way in Java to differentiate Strings created with "123" + "b" and "123b", there's no way in Bash to tell that b='"123b"' used single quotes in its definition, as opposed to e.g. b=\"123b\".
If given a variable you want to assign its value surrounded by single quotes, you can use e.g.
printf -v testvar "'%s'" "$b"
But this just adds new literal single quotes around a string. It doesn't and cannot care how b was originally quoted, because that information is stored.
To instead add a layer of escaping to a variable, so that when evaluated once it turns into a literal string identical to your input, you can use:
printf -v testvar "%q" "$b"
This will produce a value which is quoted equivalently but not necessarily identically to your original definition. For "value" (a literal with double quotes in it), it may produce \"value\" or '"value"' or '"'value'"' which all evaluate exactly to "value".
Say I want to include an escape sequence dynamically:
if [ -n $something ]; then
user="\u"
else
user="admin"
fi
PS1='$user#\h$ '
The problem is, instead of filling in the user name, my prompt looks like this:
\u#ubuntu-1$
Even if I escape the backslash (user="\\u") it still does not print out the user name. How do I get the prompt to look like this:
andreas#ubuntu-1$
Use double quotes when you are trying to interpolate variables and want them to expand.
You also have another option, instead of dealing with \u and complications with when the interpretation of it happens.
if [ -n $something ]; then
user=`whoami`
else
user="admin"
fi
PS1="$user#\h$ "