Tool: Git Bash for Windows
Problem: Trying to insert the text "\connect central" at the top of each file in a directory.
Code:
for f in $DIR/*.sql; do
sed -i "1i \\\connect central" $f
done
This does try to edit inline and insert my text, but three backslashes (like I've read everywhere) doesn't create the single backslash like I'm expected. Instead I get:
I've also tried some variants along the lines of:
for f in $DIR/*.sql; do
sed -i -e "1i `\\\connect central`" $f
done
but that throws an error of sed: -e expression #1, char 3: expected \ aftera', c',i'`
Use single quotes instead of double quotes. Backslash is an escape character inside double quotes, so you need to double it to pass it through to the sed command literally. It has no special meaning inside single quotes.
sed -i '1i \\\connect central' "$f"
To do it with double quotes (which you might need if there's variable content in the string you're inserting), you have to double all the backslashes:
sed -i "1i \\\\\\connect central" "$f"
For more information, see Difference between single and double quotes in Bash
Related
If I need to remove the following line from certain files
ob_start('ffggg_ggg');
I have tried
grep -rl "ob_start('ffggg_ggg');" /pathtosearch | xargs sed -i 's/[ob_start('ffggg_ggg');]//g'
but the rest of the characters have been removed except for single quotes.
How can I remove single quotes from a string using sed command?
I have into a text file the following line :
\[Omega]BD=100;
I would like to replace with gsed the value 100 by a shell variable (zsh shell), here 600 :
I tried :
$ i=600
$ gsed 's/\[Omega]BD=.*/\[Omega]BD=\'\\"$i"\\';/' text_to_modify.txt | grep 600
but it returns me :
\[Omega]BD=\600; and not \[Omega]BD=600;
The is an additional backslash that I don't want, I wonder how could I remove this backslash. I would like to keep the two single quotes of gsed 's/.../.../'
Using sed;
i=600
$ sed "/\[Omega]/s/[[:digit:]]\+/$i/" input_file
\[Omega]BD=600;
You may use this sed command:
i=600
sed -E "s/(\\\\\[Omega]BD=).*/\1$i;/" file
\[Omega]BD=600;
We require additional escaping i.e. \\\\ to match a single \ because we are using double quotes around full sed command.
Or we can avoid you can use this combination of single and double quotes to avoid extra escaping:
sed -E 's/(\\\[Omega]BD=).*/\1'"$i;/" file
I am trying to replace text ${APACHE_LOG_DIR} with user input in a variable $TARGETDIR
sudo sed -i -e 's|${APACHE_LOG_DIR}|$TARGETDIR|g' /etc/apache2/sites-available/$NAME.conf
Where TARGETDIR and NAME are user inputs.
Problem is that when using single quotes, the $TARGETDIR won't be parsed and put as it is. And when using double quotes, ${APACHE_LOG_DIR} is being considered an expression which is actually the text in the file I just want to be replaced.
I tried escaping in double-quotes like with forward slash like following:
sudo sed -i -e "s|\$\{APACHE_LOG_DIR\}|$TARGETDIR|g" /etc/apache2/sites-available/$NAME.conf
But then I get sed: -e expression #1, char 0: no previous regular expression
What is correct way to do this?
Use -E and write the match string as a proper regex.
Try this for instance:
sed -i -e -E "s/[$][{]APACHE_LOG_DIR[}]/$TARGETDIR/g" $NAME.conf
This question already has answers here:
sed substitution with Bash variables
(6 answers)
Closed 5 years ago.
I have a variable in a config, which I would like to replace with a value.
ROOT="rROOT"
I would like to replace that with
ROOT="$root"
So with the value of $root (Important are the quotation marks).
So far I have tried it that way
sed -i s/'ROOT=rROOT'/'ROOT="$root"'/g $directory/settings.conf
The result is that
ROOT="$root"
But this is stored in the variable $root (It is always a path)
root: /
How can I replace rROOT with the value of $root?
Sed Version: (GNU sed) 4.2.2
Ok, don't like to ruin my scripts for testing:
cat tageslog.sh | sed "s/alt=185094/alt=\${root}/g"
Use double quotes, but mask the dollar sign, so it doesn't get lost and root interpreted while calling sed.
Use ${root} instead of "$root".
sed "s/ROOT=.rRoot./ROOT=\${root}/g" $directory/settings.conf
if this works, use the -i switch:
sed -i "s/ROOT=.rRoot./ROOT=\${root}/g" $directory/settings.conf
You have different problems:
Testing with echo
I think you tested your command with
echo ROOT="rROOT" | sed s/'ROOT=rROOT'/'ROOT="$root"'/g
The double quotes won't appear in the output of the echo, so you will end up with a command working for ROOT=rROOT.
When the inputfile has qouble quotes, you do not have to insert them.
Testing with the double quotes is possible with
echo 'ROOT="rROOT"' | sed s/'ROOT=rROOT'/'ROOT="$root"'/g
Place the double quotes outside the single quotes;
You can test this with echo:
echo 'Showing "$PWD" in double quotes is "'$PWD'"'
echo 'With additional spaces the last part is " '$PWD' " '
Root vaiable has slashes that will confuse sed.
The root variable is replaced before sed tries to understand the command.
You can use another character, like #, in the sed command:
sed 's#before#after#'
When your input has double quotes:
echo 'ROOT="rROOT"' | sed 's#ROOT="rROOT"#ROOT="'$root'"#g'
# or by remembering strings
echo 'ROOT="rROOT"' | sed -r 's#(ROOT=")rROOT(")#\1'$root'\2#g'
Input without double quotes
echo 'ROOT=rROOT' | sed 's#ROOT=rROOT#ROOT="'$root'"#g'
# or by remembering strings
echo 'ROOT=rROOT' | sed -r 's#(ROOT=)rROOT#\1"'$root'"#g'
I'm using the Git Bash shell on Windows, and trying to replace a string like this in an XML file using sed:
<customTag>C:\path\to\2016a.0</customTag>
To a string like this:
<customTag>C:\path\to\2017b.0</customTag>
I can do the replacement directly like this:
$ cat test.txt
<customTag>C:\path\to\2016a.0</customTag>
$ sed -i 's^<customTag>C:\\path\\to\\2016a.0</customTag>^<customTag>C:\\path\\to\\2017b.0</customTag>^g' test.txt
$ cat test.txt
<customTag>C:\path\to\2017b.0</customTag>
But if I need to pass in variables for those strings, the replacement doesn't work.
$ cat test.txt
<customTag>C:\path\to\2016a.0</customTag>
$ export OLD_VER=2016a.0
$ export NEW_VER=2017b.0
$ sed -i 's^<customTag>C:\\path\\to\\${OLD_VER}</customTag>^<customTag>C:\\path\\to\\${NEW_VER}</customTag>^g' test.txt
$ cat test.txt
<customTag>C:\path\to\2016a.0</customTag>
Or if I use double quotes around the sed expression, I get "Invalid back reference", presumably because it thinks the 2 in the year is a reference.
$ sed -i "s^<customTag>C:\\path\\to\\${OLD_VER}</customTag>^<customTag>C:\\path\\to\\${NEW_VER}</customTag>^g" test.txt
sed: -e expression #1, char 87: Invalid back reference
What's the correct way to escape or quote this, or would I be better off using something like awk?
Keep the single quotes on the ends, and add single quotes around each variable. The single quotes prevent the shell from collapsing your double backslashes. The extra single quotes leave the variable refs outside of quotes.
Or (don't laugh) consider using forward slashes. Windows recognizes both kinds of slash as path separators; it's only the DOS command shell that does not.