How to add a string from variables to each line in a file in BASH

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8 Answers

variablesstring
90%

but i want instead of "string after each line" have a string from the following result: ,Basically, you store the value of the command inside myvar. Then, you run sed and provide the contents of $myvar as a string for the s (substitute) command., Stack Overflow for Teams Where developers & technologists share private knowledge with coworkers , Applying to math graduate schools. Should I submit a letter of recommendation from a physics professor?

If I understand you correctly, you can just save this string in a variable like so:

$ myvar = `cat filename2 | tr '\n' ' '`;
sed - e "s/$/ $myvar/" - i filename
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for i in $(cat a.txt);
do echo "Root $i";
done
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has the advantage of only using bash builtins so fewer processes will be created/destroyed so it should be a touch faster than awk or sed.,Connect and share knowledge within a single location that is structured and easy to search.,Please be sure to answer the question. Provide details and share your research!, What is the Biblical basis for civil disobedience, by not wearing a mask in the midst of COVID-19, despite health department rules?

cmd |
   while read line;
do echo "[ERROR] $line";
done

@tzrik points out that it might also make a nice bash function. Defining it like:

function prepend() {
   while read line;
   do echo "${1}${line}";
   done;
}

would allow it to be used like:

cmd | prepend "[ERROR] "
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The third line prints out each array element as string (%s) followed by a newline (\n).,There can be whitespace around the array elements, on the first line I added spaces between the string and brackets, on the second I omitted spaces, to show it works both ways.,because when you print the string without quotes, newline are converted to spaces.,The second line adds one more element to the array with the += operator. Here the quotes are optional, because there is no whitespace.

In bash you can use the syntax

str = $ 'Hello World\n===========\n'

Also printf builtin allows to save the resulting output to a variable

printf - v str 'Hello World\n===========\n'

If in the following you need to print the string, you should use double quotes, like in the following example:

echo "$str"
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I want to insert a text from variable at the certain line of a text file.,I want to insert $var into second line, but sed does not read the content of the variable:,You call variables in sed with double quotes, Student asked me if it is necessary to simplify fractions at the end of answering a question. I'm not sure how to respond

You call variables in sed with double quotes

sed - i - e "2i$var"
bar
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Example 10-1. Inserting a blank line between paragraphs in a text file,A Bash script may invoke the string manipulation facilities of awk as an alternative to using its built-in operations.,For more on string manipulation in scripts, refer to Section 10.2 and the relevant section of the expr command listing.,A simple emulation of getopt using substring-extraction constructs.

stringZ = abcABC123ABCabc

echo $ {
   #stringZ
}
# 15
echo `expr length $stringZ`
# 15
echo `expr "$stringZ" : '.*'`
# 15
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In this topic, we have explained how to add or concatenate strings in Bash Shell Scripting.,Most of the popular programming languages provide support for append operator (+=) which is the combination of the plus and equal sign. It will add new strings to the end of the string variable.,This command will concatenate the values of str1 and str2 and store it in a third variable str3.,In bash, printf is a function which is used to print and concatenate the strings.

We welcome you on Javatpoint.
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Both the files can be concatenated by using the following command:,Concatenate Strings in Bash with awk,Concatenate Strings in Bash with echo,Concatenate Strings in Bash with join

$ string1 = "Stuck"
$ string2 = "Together"
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