I have the following string variable defined in bash as version
Uploaded registry/version1.3.1
I need to escape the / twice so that the string looks like:
registry\\/version1.3.1
Is there a way to use sed to find and replace all / to \\/?
One backslash is used to change an argument to text or vice versa.
echo 'Uploaded registry/version1.3.1' | sed 's/\//\\\\\//g'
Uploaded registry\\/version1.3.1
In this case you need \\ for one backslash and \/for a slash.
Using sed
You need two backslashes, \\, in the RHS (right-hand side) of the sed command to replaces with a single backslash.
Also, it is a good idea to use a character other than / as a regex delimiter to avoid overescaping.
You can thus use
sed 's,/,\\\\/,g'
See this online demo:
echo 'Uploaded registry/version1.3.1' | sed 's,/,\\\\/,g'
# => Uploaded registry\\/version1.3.1
Using string manipulation
You may also just use string manipulation in Bash:
s='Uploaded registry/version1.3.1'
echo "${s//\//\\\\\/}"
# => Uploaded registry\\/version1.3.1
Here, the backslash needs doubling again, and a single \ is added to escape /s. Note that "${s//a/b} means: replace all occurrences of a with b in s variable.
Related
I want to replace some strings with other strings in a folder containing .ly files (.ly files are files used to write music, which can then be converted to svg files). One problem is that the files contain backslashes (\).
Anyway, what I want to do is to replace the following strings:
\f with \fffff
\p with \ppppp
mordent with reverseturn
r4 with \mordent
Each string I want to replace (and each string it is replaced for) has a space in the end. This is because I don't want strings like
\pt to be replaced with \pppppt
Similarly, because backslashes matter, strings like
\ff should stay the same (only f with a slash before and a space after should be replaced).
The code that I am using to achieve this is:
for f in *.ly
do
filename="${f}"
sed -i -- "s#\p #\ppppp #g; s#\f #\fffff #g; s#mordent #reverseturn #g; s#r4 #\maxima #g" $filename;
done
I am using delimited # instead of backslash exactly to achieve this.
However, the program is giving some totally weird behavior. In particular:
\f stays the same (wrong behavior, the right behavior is to get transformed to \fffff)
\p is converted to \ppppp (correct behavior)
\stemUp is converted to \stemUppppp (wrong behavior, the right behavior is to remain as it was)
This is perplexing me and giving me a headache. In particular, why it works correctly for \p but not for \f considering that it is the exact same code.
For reference, I attached a file before and after applying the sed commands.
Thanks in advance for any help!
NB: I am using Ubuntu 16.04 and sed (GNU 4.2.2).
$ echo '12p3 p \p foo' | sed 's/\p /\ppppp /g'
12p3 ppppp \ppppp foo
$ echo '12p3 p \p foo' | sed 's/\\p /\\ppppp /g'
12p3 p \ppppp foo
\ is a meta-character, to match it literally, it needs to be escaped, i.e \\
\ is special within double quotes too(because of bash, nothing to do with sed) - so don't use double quotes unless needed(for ex: sed substitution with bash variables). See also Difference between single and double quotes in Bash
File Content(file.txt):
table=$table_name
data=$data_name
Shell Script:
name=kush_123
cat file.txt | grep 'table' | sed "s\table_name\$name\g"
Expected output:
table=$kush_123
This gives error
unterminated s command
if the name variable has _ in it.
If you really want to use a backslash as a delimiter, it needs to be escaped itself so that the double-quoted string preserves it before passing to sed:
sed "s\\table_name\\$name\\g"
Otherwise, sed receives the string stable_name$nameg as its script. (\t, \$, and \g expand to t, $, and g, respectively). In this case, the letter t (as it immediately follows the s) is used as the delimiter, and the error results because there aren't enough ts in the result to provide a complete command.
Of course, if you try this, sed should complain that a backslash cannot be used as the delimiter for the s command. Use a different character:
sed "s/table_name/$name/g"
In general, building such scripts dynamically is fragile, because it assumes you know the value of $name doesn't contain your chosen delimiter.
On more investigation i found out the variable name has trailing spaces as the variable value was passed from python code. I trimmed extra spaces and it worked. Thanks :)
I'm trying to write a script in bash which extracts a database name from a PHP file. For example I want to copy CRM_123456789 from the below line:
$sugar_config['dbconfig']['db_name'] = 'CRM_123456789';
I have tried using sed, so essentially I want to copy the text between
['db_name'] = '
and
';
sed -n '/['db_name'] = /,/';/p' myfile.php
However this does not return anything. Does anyone know what I'm doing wrong?
Thanks
You cannot nest single quotes. Your expression evaluates to single-quoted /[ next to unquoted db_name where clearly you want to match on a literal single quote.
One workaround is to use double quotes for the outermost quoting, but make sure you make any necessary changes, because double quotes are weaker than single quotes in the shell. In your case, there's nothing to change in that respect, though.
However, you also appear to misunderstand how sed address expressions work. They identify lines, not substrings on a line. So your script would print between a line matching ['db_name'] and a line matching ';. To extract something from within a line, the common idiom is to substitute out the parts you don't want, then print what's left.
Also, because opening square bracket is a metacharacter in sed, you need to backslash-escape it to match it literally.
sed -n "s/.*\['db_name'] = '\([^']*\)'.*/\1/p" myfile.php
This matches up through ['db_name'] = ', then captures whatever is inside the single-quoted string into \1, then matches anything from the next single quote through the end of line, and substitutes it with just the captured string; and prints that line after performing the substitution.
If the config file supports variable whitespace, a useful improvement would be to allow for optional whitespace around the equals sign, and possibly also within the square brackets. [ ]* will match zero or more spaces (the square brackets aren't really necessary around a single space, but I include them here for legibility reasons).
You could try the below sed command.
$ sed -n "s/.*\['db_name'\] = '\([^']*\)';.*/\1/p" file
CRM_123456789
I have file with comments like this:
\$max_servers = 2;
\#\## BLOCKED ANYWHERE
I'm trying to
Replace all instances of \$ with $.
Replace all instances of \#\## with ###.
I wonder how I can go about doing that via sed or awk
What I have tried so far without much success using vi or vim
%s/^\//gc
%s/^#/\\/###/gc
Thank you
Another option to replace all [#$] in one pass is to use the following regular expression. The following is VI syntax:
:%s/\\\([$#]\)/\1/g
Replace the characters in the brackets [] with whatever you need if its more than just # and $.
The first \\ is a backslash - escaped since its inside a regular expression
The expression between the \( and \) is saved and later used in the replacement as \1.
Escaping backslash will work
#echo "\#\##"| sed "s/\\\\#\\\\##/###/g"
###
# echo "\\$"| sed "s/\\\\\\$/$/g"
$
In order to replace a backslash, you have to double it up, so it can quote itself much the way other special characters must be quoted. You can use sed instead of vim to help automate the process a bit:
$ sed -e 's/^\\\$/$/' -e 's/^\\#\\##/###/' $file > $new_file
Note that you have to put a backslash in front of dollar signs since they are used to mark an end of line in regular expressions. That's why I have \\\$ in my first expression. One backslash to quote the backslash and another backslash to quote the dollar sign.
By the way, these same sed expressions will also work inside Vim depending upon your Vim settings.
You escape special characters with the backslash. So for example, to replace everything with \$, you would do
%s/\\\$/$/g
sed 's|^\\\([$#]\)\\\{0,1\}|\1|' YourFile
work for your sample bu will also remove the 2 \ in \$\ ...,
I have a file with a lot of lines, two of them are:
videoId: 'S2Rgr6yuuXQ'
var vid_seq=1;
in a shell script, I have two variables,
for id, the value is always 11 characters/numbers
id='fsafsferii2'
id_seq=80
I want to modify these two lines with id and id_seq
videoId: 'fsafsferii2'
var vid_seq=80;
I used
sed -i 's/\(videoId: \).*\\1'${id}'/\2' file
but there are errors, what is wrong with my script?
thanks
The grep command won't "replace" text, it is for "global regular expression print". But sed will.
sed -i'' '/^videoId: /s/: .*/: '"$id"'/;/^var vid_seq=/s/=.*/='"$id_seq"';/'
I'm not a big fan of inserting variables into sed scripts this way, but sed is simple, and provides no mechanism for actually using actual variables on its own. If you're going to do this, include some format checking for the two variables to make sure they contain the data you want them to contain, before you run this sed script. An accidental / in a variable would cause the sed script to fail.
UPDATE per comments:
Here's a successful test:
$ id=fsafsferii2
$ id_seq=80
$ cat inp686
videoId: 'S2Rgr6yuuXQ'
var vid_seq=1;
$ sed '/^videoId: /s/: .*/: '"$id"'/;/^var vid_seq=/s/=.*/='"$id_seq"';/' < inp686
videoId: fsafsferii2
var vid_seq=80;
$
Of course, you'll need to do some quote magic to get the single quotes into your videoId, but I'm sure you can figure that out yourself.
UPDATE 2
According to sed's man page, the substitute command is in the form:
[2addr]s/regular expression/replacement/flags
The [2addr] means you can specify up to two "addresses", which can be line numbers or regular expressions to match. So the s (substitute) command can take a line, a range, a match, or a span between matches. In our case, we're just using a single match to identify what lines we want to execute the substitution on.
The script above is made up of two sed commands, separated by a semicolon.
/^videoId: / -- Match lines that start with the word videoId:...
s/: .*/: '"$id"'/; -- Substitute all text from the colon to the end of the line with whatever is in the $id environment variable.
/^var vid_seq=/ -- Match lines that ... meh, as above.
s/=.*/='"$id_seq"';/ -- Substitute all text from the equals sign on with $id_seq.
Note that the '"$id"' construct means that we are exiting the single quotes, then immediately entering double quotes for the expansion of the variable ... then exiting the double quotes and going back into a new set of single quotes. Sed scripts are safest inside single quotes because of the frequent use of characters that might be interpreted by a shell.
Note also that because sed's substitute command uses a forward slash as a delimiter, the $id and $id_seq variables may not contain a slash. If they might, you can switch to a different delimiter.
What is wrong with:
sed -i 's/\(videoId: \).*\\1'${id}'/\2' file
Missing the third delimiter (/). Valid syntax is s/regex/replace/
Incorrect regex pattern (let's assume ${id} has been substituted)
\(videoId: \).*\\1fsafsferii2
is telling it to match a string that looks like this:
videoId: anything\1fsafsferii2
(\\ in regex matches literal backslash, so \\1 would match a literal backslash followed by 1 instead of 1st sub-expression)
Replace the matched string with \2
But since there is only one set of parentheses, \2 is actually empty.
Also, since the regex pattern in 2. doesn't match anything, nothing is replaced.
This should work (GNU sed)
sed -i 's/\(videoId: \).*/\1 \x27'${id}'\x27/
s/\(var vid_seq=\).*/\1'${id_seq}'\;/' file
Note:
\x27 is the hexadecimal representation of single quote (to prevent clashing with the other single quote)
\; for literal semicolon. If ; is not escaped, it's interpreted to terminate the s command in sed.