This question already has answers here:
How do I replace single quotes with another character in sed?
(6 answers)
Closed 5 months ago.
Trying to put ' before each line of text and ' at the end of each line of text.
I have been using sed 's/^/1/' file.txt to replace to begging of each line and sed 's/$/0/' file.txt to replace the end of each line.
What I am trying to make work is sed 's/^/'/' and sed 's/$/'/'
This would format my file to make each line reach as a command, when applied to a separate script.
echo abc | sed "s/.*/'&'/"
Output:
'abc'
From man sed:
The replacement may contain the special character & to refer to that portion of the pattern space which
matched
Related
This question already has answers here:
How to remove the leading and trailing space from each line of a file using shell script?
(2 answers)
Closed 8 months ago.
The community reviewed whether to reopen this question 8 months ago and left it closed:
Original close reason(s) were not resolved
I am have the following text:
>seq1
--A--CGT-A--
>seq2
-GA-T-A-CC--
I would like to remove all "-" from the beginning and the end of the lines, i.e., keeping the "-" between the letters. Expected output:
>seq1
A--CGT-A
>seq2
GA-T-A-CC
I have tried the following sed, but it deletes only the "-" from the beginning.
sed 's/^\(-\)*//'
Can anyone help, please?
You can use
sed 's/^-*\|-*$//g' file
sed -E 's/^-*|-*$//g' file
sed -E 's/^-+|-+$//g' file
Each of the commands removes hyphens from the start and from the end of the lines. Note the g flag that enables multiple matching on the same line.
To support cases with leading or trailing whitespaces, add [[:space:]] / \s:
sed 's/^\s*-*\|-*\s*$//g'
sed -E 's/^[[:space:]]*-*|-*[[:space:]]*$//g'
Note: \s and \| examples are only valid for GNU sed.
See the online demo:
#!/bin/bash
s='>seq1
--A--CGT-A--
>seq2
-GA-T-A-CC--'
sed 's/^-*\|-*$//g' <<< "$s"
Output:
>seq1
A--CGT-A
>seq2
GA-T-A-CC
This removes leading and trailing dashes on every line not beginning with > (including indented >).
sed -E '/^[[:space:]]*>/!{s/^-+|-+$//}'
Consider allowing for indented dashes: s/[[:space:]]*-//.
This question already has answers here:
How to escape the ampersand character while using sed
(3 answers)
Closed 2 years ago.
My config file looks like:
KEY1=VALUE1
URL=https://drive.google.com/uc?export=download&id=myhash
KEY3=VALUE3
I'm trying to use sed to replace the URL value with another one. I got to the following:
sed -i.bak 's#URL=.*#URL=https://drive.google.com/uc?export=download&id=mynewhash#g' file.txt
But that doesn't seem to work, as I'm getting:
URL=https://drive.google.com/uc?export=downloadURL=https://drive.google.com/uc?export=download&id=mynewhash=myhash
What am I missing? Thanks
& is a special character in the replacement string provided to the s command of sed. It represents the string that matches the entire regex used to search (URL=.* in your example).
In order to represent itself it needs to be escaped with \:
sed -i.bak 's#URL=.*#URL=https://drive.google.com/uc?export=download\&id=mynewhash#g' file.txt
Type man sed in your terminal to read its documentation or read the documentation of sed online.
This question already has answers here:
Using different delimiters in sed commands and range addresses
(3 answers)
Closed 4 years ago.
I want to use sed on some text that contains backslashes, and want to avoid lots of escaped \/ characters.
How can I change the delimiter or separator character to be other than /?
In GNU sed, simply swap out the / for the character you wish to use:
% echo /// | sed 's_/_x_g'
xxx
\ can also be used, and must not be escaped (it fails when escaped as \\):
% echo xxx | sed 's\x\y\g'
yyy
This question already has answers here:
Shell variables in sed script [duplicate]
(5 answers)
Closed 8 years ago.
I want to delete words into a line. For example:
I want to delete one word in this line
And I want to delete 'one' to obtain:
I want to delete word in this line
By passing the word through a variable. So far I have got:
WORD=one ; sed -n 's/"$WORD"//g' file.txt > newfile.txt
But, it doesn't do anything. Why not? And how can I make it work?
WORD=one ; sed -e "s/$WORD//g" file.txt > newfile.txt
the key moment is variable expansion. You have to be careful though because shell variable expansion may be sometimes not what you want. In hard cases you have to do something like this:
EXPANDVAR=one; NOEXPANDVAR=another; sed -e 's/'"$EXPANDVAR"'$NOEXPANDVAR//g' file.txt > newfile.txt
In this case sed will replace (remove) pattern one$NOEXPANDVAR , literally.
This question already has answers here:
Using different delimiters in sed commands and range addresses
(3 answers)
Closed 1 year ago.
Changing the delimiter slash (/) to pipe (|) in the substitute command of sed works like below
echo hello | sed 's|hello|world|'
How can I change the delimiter slash (/) to pipe (|) in the sed insert command below?
echo hello | sed '/hello/i world'
I'm not sure what is intended by the command you mentioned:
echo hello | sed '/hello/i world'
However, I presume that you want to perform certain action on lines matching the pattern hello. Lets say you wanted to change the lines matching the pattern hello to world. In order to accomplish that, you can say:
$ echo -e "something\nhello" | sed '\|hello|{s|.*|world|}'
something
world
In order to match lines using a regexp, the following forms can be used:
/regexp/
\%regexp%
where % may be replaced by any other single character (note the preceding \ in the second case).
The manual provides more details on this.
The answer to the question asked is:
echo hello | sed '\|hello|i world'
That is how you would prepend a line before a line matching a path, and avoid Leaning Toothpick Syndrome with the escapes.