So not sure, but i tried the following and it didn't work.
What string can i use to replace a directory string in sed?
sed 's"/usr/lib64/$id""/home/user1/$id"/g' 1.php > 1_new.php
Because your strings have slashes in them, it is convenient to use a different separator in the substitution expression. Here, I use | as the separator. If, for simplicity, we ignore the double-quotes inside your regular expression, we could use:
sed "s|/usr/lib64/$id|/home/user1/$id|g" 1.php > 1_new.php
If we include the double-quotes, then quoting because a bit more complex:
sed 's|"/usr/lib64/'"$id"'"|"/home/user1/'"$id"'"|g' 1.php > 1_new.php
I assume that you intend for $id to be replaced by the value of the shell variable id. If so, it is important in both cases that the expression $id not be inside single-quotes as they inhibit variable expansion.
Discussion of Quoting
The quoting in the second case may look ugly. To help explain, I will add some spaces to separate the sections of the string:
sed 's|"/usr/lib64/' "$id" '"|"/home/user1/' "$id" '"|g' # Don't use this form.
From the above, we can see that the sed command is made up of a single-quoted string, 's|"/usr/lib64/' followed by a double-quoted string, "$id", followed by a single-quoted string, '"|"/home/user1/', followed by a double-quoted string, "$id", followed by a single-quoted string, '"|g'. Because everything is in single-quotes except that which we explicitly want the shell to expand, this is generally the approach that is safest against surprises.
Alternate Quoting Style
The following quoting style may seem simpler:
sed "s|\"/usr/lib64/$id\"|\"/home/user1/$id\"|g" 1.php > 1_new.php
In the above, the sed command is all one double-quoted string. Double-quotes can be included within double-quoted strings by escaping them as \". This style is fine as long as you are confident that you know that the shell won't expand anything except what you want expanded.
Related
I am looking to translate this regular expression into grep flavour:
I am trying to filter all lines that contain refs/changes/\d+/$VAR/
Example of line that should match, assuming that VAR=285900
b3fb1e501749b98c69c623b8345a512b8e01c611 refs/changes/00/285900/9
Current code:
VAR=285900
grep 'refs/changes/\d+/$VAR/' sample.txt
I am trying to filter all lines that contain refs/changes/\d+/$VAR/
That would be
grep "refs/changes/[[:digit:]]\{1,\}/$VAR/"
or
grep -E "refs/changes/[[:digit:]]+/$VAR/"
Note that the \d+ notation is a perl thing. Some overfeatured greps might support it with an option, but I don't recommend it for portability reasons.
inside simple quotes I cannot use variable expansion
You can mix and match quotes:
foo=not; echo 'single quotes '"$foo"' here'
with double quotes it does match anything.
It's not clear what you're doing, so we can't say why it doesn't work. It should work. There is no need to escape forward slashes for grep, they don't have any special meaning.
I'm trying to write a bash function that would escape all double quotes within single quotes, eg:
'I need to escape "these" quotes with backslashes'
would become
'I need to escape \"these\" quotes with backslashes'
My take on it was:
Find pairs of single quotes in the input and extract them with grep
Pipe into sed, escape double quotes
Sed again the whole input and replace grep match with sedded match
I managed to get it working to the part of having correctly escaped quotes section, but replacing it in the whole input fails.
The script code copypaste:
# $1 - Full name, $2 - minified name
adjust_quotes ()
{
SINGLE_QUOTES=`grep -Eo "'.*'" $2`
ESCAPED_QUOTES=`echo $SINGLE_QUOTES | sed 's|"|\\\\"|g'`
sed -r "s|'.*'|$ESCAPED_QUOTES|g" "$2" > "$2.escaped"
mv "$2.escaped" $2
echo "Quotes escaped within single quotes on $2"
}
Random additional questions:
In the console, escaping the quote with only two backslashes works, but when code is put in the script - I need four. I'd love to know
Could I modify this code into a loop to escape all pairs of single quotes, one after another until EOF?
Thanks!
P.S. I know this would probably be easier to do in eg. python, but I really need to keep it in bash.
Using BASH string replacement:
s='I need to escape "these" quotes with backslashes'
r="${s//\"/\\\"}"
echo "$r"
I need to escape \"these\" quotes with backslashes
Here's a pure bash solution, which does the transformation on stdin, printing to stdout. It reads the entire input into memory, so it won't work with really enormous files.
escape_enclosed_quotes() (
IFS=\'
read -d '' -r -a fields
for ((i=1; i<${#fields[#]}; i+=2)); do
fields[i]=${fields[i]//\"/\\\"}
done
printf %s "${fields[*]}"
)
I deliberately enclosed the body of the function in parentheses rather than braces, in order to force the body to run in a subshell. That limits the modification of IFS to the body, as well as implicitly making the variables used local.
The function uses the read builtin to read the entire input (since the line delimiter is set to NUL with -d '') into an array (-a) using a single quote as the field separator (IFS=\'). The result is that the parts of the input surrounded with single quotes are in the odd positions of the array, so the function loops over the odd indices to do the substitution only for those fields. I use bash's find-and-replace syntax instead of deferring to an external utility like sed.
This being bash, there are a couple of gotchas:
If the file contains a NUL, the rest of the file will be ignored.
If the last line of the file does not end with a newline, and the last character of that line is a single quote, it will not be output.
Both of the above conditions are impossible in a portable text file, so it's probably OK. All the same, worth taking note.
The supplementary question: why are the extra backslashes needed in
ESCAPED_QUOTES=`echo $SINGLE_QUOTES | sed 's|"|\\\\"|g'`
Answer: It has nothing to do with that line being in a script. It has to do with your use of backticks (...) for command substitution, and the idiosyncratic and often unpredictable handling of backslashes inside backticks. This syntax is deprecated. Do not use it. (Not even if you see someone else using it in some random example on the internet.) If you had used the recommended $(...) syntax for command substitution, it would have worked as expected:
ESCAPED_QUOTES=$(echo $SINGLE_QUOTES | sed 's|"|\\"|g')
(More information is in the Bash FAQ linked above.)
This is driving me insane. Here's my dilemma, I have a file in which I need to make a match. Usually I use Perl and it works like a charm but in this case I am writing a shell script and for some reason it is throwing errors.
Here is what I am trying to match:
loop_loopStorage_rev='latest.integration'
I need to match loop and latest.integration.
This is my regex:
^(?!\#)(loop_.+rev).*[\'|\"](.*)[\'|\"]$
When I use this in a Perl script, $1 and $2 give me the appropriate output. If I do this:
perl -nle "print qq{$1 => $2} while /^(?!#)(loop_.+rev).+?[\'|\"](.+?)[\'|\"]$/g" non-hadoop.env
I get the error:
-bash: syntax error near unexpected token `('
I believe it has something to do with the beginning part of my regex. So my real question is would there be an easier solution using sed, egrep or awk? If so, does any one know where to begin?
Using single quotes around your arguments to prevent special processing of $, \, etc. If you need to include a single quote within, the generic solution is to use '\''. In this particular case, however, we can avoid trying to include a ' by using the equivalent \x27 in the regex pattern instead.
perl -nle'
print "$1 => $2"
while /^(?!#)(loop_.+rev).+?[\x27\"|](.+?)[\x27\"|]$/g;
' non-hadoop.env
[I added some line breaks for readability. You can actually leave them in if you want to, but you don't need to.]
Note that there are some problems with your regex pattern.
(?!\#)(loop_.+rev) is the same as (loop_.+rev) since l isn't #, so (?!\#) isn't doing whatever you think it's doing.
[\'|\"] matches ', " and |, but I think you only meant it to match ' and ". If so, you want to use [\'\"], which can be simplified to ['"].
Don't use the non-greedy modifier (? after +, *, etc). It's used for optimization, not for excluding characters. In fact, the second ? in your pattern has absolutely no effect, so it's not doing what you think it's doing.
Fixed?
perl -nle'
print "$1 => $2"
while /^(loop_.+rev).+[\x27"]([^\x27"]*)[\x27"]$/g;
' non-hadoop.env
Double quotes cause Bash to replace variable references like $1 and $2 with the values of these shell variables. Use single quotes around your Perl script to avoid this (or quote every dollar sign, backtick, etc in the script).
However, you cannot escape single quotes inside single quotes easily; a common workaround in Perl strings is to use the character code \x27 instead. If you need single-quoted Perl strings, use the generalized single-quoting operator q{...}.
If you need to interpolate a shell variable name, a common trick is to use "see-saw" quoting. The string 'str'"in"'g' in the shell is equal to 'string' after quote removal; you can similarly use adjacent single-quoted and double-quoted strings to build your script ... although it does tend to get rather unreadable.
perl -nle 'print "Instance -> $1\nRevision -> $2"
while /^(?!#)('"$NAME"'_.+rev).+[\x27"]([^\x27"]*)[\x27"]$/g' non-hadoop.en
(Notice that the options -nle are not part of the script; the script is the quoted argument to the -e option. In fact perl '-nle script ...' coincidentally works, but it is decidedly unidiomatic, to the point of confusing.)
I ended up figuring out due to all of you guys help. Thanks again. Here is my final command
perl -nle 'print "$1 $2" while /^($ENV{NAME}_.+rev).+\x27(.+)\x27/g;' $ENVFILE
I have a file with plenty of ; characters that act as a delimiter/separator. At some places, they are redundant. There are character sequences that are of the forms ;;, ;;;, ; ;, etc. Is there a way to get rid of one of those semicolons and what they have in between only if there is nothing in between them other than blanks?
In other words, I want to convert text; ; text; text; to text; text; text; by replacing either one of the forms I mentioned above with just one ;. I thought of using sed, but if another command can do the job, I'm of course ok with it.
I am using OS X Yosemite.
This should work:
sed 's/;\( *;\)\{1,\}/;/g'
An alternative would be
sed 's/\(; *\)\{1,\}/; /g'
With GNU sed, you could use \+ instead of \{1,\} instead of \+. You could also use extended regular expressions (-E on BSD sed, -r with Gnu sed) for a more readable regular expression:
sed -E 's/;( *;)+/;/g'
sed -E 's/(; *)+/;/g'
The difference between the two forms is that the second one will always make sure that there is a space after a semicolon. (Neither fixes spaces before the first semicolon in a series. Add a * to the beginning of the patterns if that's what you want.)
we have an sed command in our script to replace the file content with values from variables
for example..
export value="dba01upc\Fusion_test"
sed -i "s%{"sara_ftp_username"}%$value%g" /home_ldap/user1/placeholder/Sara.xml
the sed command ignores the special characters like '\' and replacing with string "dba01upcFusion_test" without '\'
It works If I do the export like export value='dba01upc\Fusion_test' (with '\' surrounded with ‘’).. but unfortunately our client want to export the original text dba01upc\Fusion_test with single/double quotes and he don’t want to add any extra characters to the text.
Can any one let me know how to make sed to place the text with special characters..
Before Replacement : Sara.xml
<?xml version="1.0" encoding="UTF-8"?>
<ser:service-account >
<ser:description/>
<ser:static-account>
<con:username>{sara_ftp_username}</con:username>
</ser:static-account>
</ser:service-account>
After Replacement : Sara.xml
<?xml version="1.0" encoding="UTF-8"?>
<ser:service-account>
<ser:description/>
<ser:static-account>
<con:username>dba01upcFusion_test</con:username>
</ser:static-account>
</ser:service-account>
Thanks in advance
You cannot robustly solve this problem with sed. Just use awk instead:
awk -v old="string1" -v new="string2" '
idx = index($0,old) {
$0 = substr($0,1,idx-1) new substr($0,idx+length(old))
}
1' file
Ah, #mklement0 has a good point - to stop escapes from being interpreted you need to pass in the values in the arg list along with the file names and then assign the variables from that, rather than assigning values to the variables with -v (see the summary I wrote a LONG time ago for the comp.unix.shell FAQ at http://cfajohnson.com/shell/cus-faq-2.html#Q24 but apparently had forgotten!).
The following will robustly make the desired substitution (a\ta -> e\tf) on every search string found on every line:
$ cat tst.awk
BEGIN {
old=ARGV[1]; delete ARGV[1]
new=ARGV[2]; delete ARGV[2]
lgthOld = length(old)
}
{
head = ""; tail = $0
while ( idx = index(tail,old) ) {
head = head substr(tail,1,idx-1) new
tail = substr(tail,idx+lgthOld)
}
print head tail
}
$ cat file
a\ta a a a\ta
$ awk -f tst.awk 'a\ta' 'e\tf' file
e\tf a a e\tf
The white space in file is tabs. You can shift ARGV[3] down and adjust ARGC if you like but it's not necessary in most cases.
Update with the benefit of hindsight, to present options:
Update 2: If you're intent on using sed, see the - somewhat cumbersome, but now robust and generic - solution below.
If you want a robust, self-contained awk solution that also properly handles both arbitrary search and replacement strings (but cannot incorporate regex features such as word-boundary assertions), see Ed Morton's answer.
If you want a pure bash solution and your input files are small and preserving multiple trailing newlines is not important, see Charles Duffy's answer.
If you want a full-fledged third-party templating solution, consider, for instance, j2cli, a templating CLI for Jinja2 - if you have Python and pip, install with sudo pip install j2cli.
Simple example (note that since the replacement string is provided via a file, this may not be appropriate for sensitive data; note the double braces ({{...}})):
value='dba01upc\Fusion_test'
echo "sara_ftp_username=$value" >data.env
echo '<con:username>{{sara_ftp_username}}</con:username>' >tmpl.xml
j2 tmpl.xml data.env # -> <con:username>dba01upc\Fusion_test</con:username>
If you use sed, careful escaping of both the search and the replacement string is required, because:
As Ed Morton points out in a comment elsewhere, sed doesn't support use of literal strings as replacement strings - it invariably interprets special characters/sequences in the replacement string.
Similarly, the search string literal must be escaped in a way that its characters aren't mistaken for special regular-expression characters.
The following uses two generic helper functions that perform this escaping (quoting) that apply techniques explained at "Is it possible to escape regex characters reliably with sed?":
#!/usr/bin/env bash
# SYNOPSIS
# quoteRe <text>
# DESCRIPTION
# Quotes (escapes) the specified literal text for use in a regular expression,
# whether basic or extended - should work with all common flavors.
quoteRe() { sed -e 's/[^^]/[&]/g; s/\^/\\^/g; $!a\'$'\n''\\n' <<<"$1" | tr -d '\n'; }
# '
# SYNOPSIS
# quoteSubst <text>
# DESCRIPTION
# Quotes (escapes) the specified literal string for safe use as the substitution string (the 'new' in `s/old/new/`).
quoteSubst() {
IFS= read -d '' -r < <(sed -e ':a' -e '$!{N;ba' -e '}' -e 's/[&/\]/\\&/g; s/\n/\\&/g' <<<"$1")
printf %s "${REPLY%$'\n'}"
}
# The search string.
search='{sara_ftp_username}'
# The replacement string; a demo value with characters that need escaping.
value='&\1%"'\'';<>/|dba01upc\Fusion_test'
# Use the appropriately escaped versions of both strings.
sed "s/$(quoteRe "$search")/$(quoteSubst "$value")/g" <<<'<el>{sara_ftp_username}</el>'
# -> <el>&\1%"';<>/|dba01upc\Fusion_test</el>
Both quoteRe() and quoteSubst() correctly handle multi-line strings.
Note, however, given that sed reads a single line at at time by default, use of quoteRe() with multi-line strings only makes sense in sed commands that explicitly read multiple (or all) lines at once.
quoteRe() is always safe to use with a command substitution ($(...)), because it always returns a single-line string (newlines in the input are encoded as '\n').
By contrast, if you use quoteSubst() with a string that has trailing newlines, you mustn't use $(...), because the latter will remove the last trailing newline and therefore break the encoding (since quoteSubst() \-escapes actual newlines, the string returned would end in a dangling \).
Thus, for strings with trailing newlines, use IFS= read -d '' -r escapedValue < <(quoteSubst "$value") to read the escaped value into a separate variable first, then use that variable in the sed command.
This can be done with bash builtins alone -- no sed, no awk, etc.
orig='{sara_ftp_username}' # put the original value into a variable
new='dba01upc\Fusion_test' # ...no need to 'export'!
contents=$(<Sara.xml) # read the file's content into
new_contents=${contents//"$orig"/$new} # use parameter expansion to replace
printf '%s' "$new_contents" >Sara.xml # write new content to disk
See the relevant part of BashFAQ #100 for information on using parameter expansion for string substitution.