I work on shell script and I want to remove all space characters in a string.
On another question I saw a sed command for replacing and tried to use it with sending null character in it:
echo \0 | sed "s/ /${text}/"
But it did not work.
Any other way to do this?
This deletes all space characters in the input:
echo some text with spaces | tr -d ' '
Another way using sed:
echo some text with spaces | sed -e 's/ //g'
But... In your example there are no spaces, and it looks like you want to replace spaces with the content of the variable $text... So not 100% sure this is what you're looking for. So if not, then please clarify.
This was my use case:
Multiple key values that should go on a single string. I'd like to split the string to make them easier to read.
SPLIT=" \
KEY_1=$VALUE_1, \
KEY_2=$VALUE_2, \
KEY_3=$VALUE_3 \
"
JOINED="$(echo "$SPLIT" | sed "s/ //g")" # REMOVE SPACES
echo $JOINED
Related
I am trying to create a string eg (file1.txt,file2.txt,file3.txt).
All these 3 files names are within a file.
ls file*.txt > lstfiles.txt
while read filename; do
filename+=$line","
done <lstfiles.txt
This returns me with output:
file1.txt,file2.txt,file3.txt,
How can I find the last iteration of the loop so I dont add another comma at the end.
Required output:
file1.txt,file2.txt,file3.txt
For your use case I would rather get rid of the while loop and combine sedand tr commands like so:
sed -e '$ ! s/$/,/g' lstfiles.txt | tr -d '\n'
Where sed command replace each line endings execept the last one with a comma and tr command remove the linebreaks.
Probably avoid using ls in scripts though.
printf '%s,' file*.txt |
sed 's/,$/\n/'
assuming your sed recognizes \n to be a newline, and copes with input which doesn't have a final newline.
I wanted to use grep to exclude words from $lastblock by using a pipeline, but I found that grep works only for files, not for stdout output.
So, here is what I'm using:
lastblock="./2.json"
echo $lastblock | sed '1,/firstmatch/d;/.json/,$d'
I want to exclude ./ and .json, keeping only what is between.
This sed command is correct for this purpose, but how to escape the ./ replacing firstmatch so it can work?
Thanks in advance!
Use bash's Parameter Substitution
lastblock="./2.json"
name="${lastblock##*/}" # strips from the beginning until last / -> 2.json
base="${name%.*}" # strips from the last . to the end -> 2
but I found that grep works only for files, not for stdout output.
here it is. (if your grep supports the -P flag.
lastblock="./2.json"
echo "$lastblock" | grep -Po '(?<=\./).*(?=\.)'
but how to escape the ./
With sed(1), escape it using a back slash \
lastblock="./2.json"
echo "$lastblock" | sed 's/^\.\///;s/\..*$//'
Or use a different delimiter like a pipe |
sed 's|^\./||;s|\..*$||'
with awk
lastblock="./2.json"
echo "$lastblock" | awk -F'[./]+' '{print $2}'
Starting from bashv3, regular expression pattern matching is supported using the =~ operator inside the [[ ... ]] keyword.
lastblock="./2.json"
regex='^\./([[:digit:]]+)\.json'
[[ $lastblock =~ $regex ]] && echo "${BASH_REMATCH[1]}"
Although a P.E. should suffice just for this purpose.
I wanted to use grep to exclude words from $lastblock by using a pipeline, but I found that grep works only for files, not for stdout output.
Nonsense. grep works the same for the same input, regardless of whether it is from a file or from the standard input.
So, here is what I'm using:
lastblock="./2.json"
echo $lastblock | sed '1,/firstmatch/d;/.json/,$d'
I want to exclude ./ and .json, keeping only what is between. This sed
command is correct for this purpose,
That sed command is nowhere near correct for the stated purpose. It has this effect:
delete every line from the very first one up to and including the next subsequent one that matches the regular expression /firstmatch/, AND
delete every line from the first one matching the regular expression /.json/ to the last one of the file (and note that . is a regex metacharacter).
To remove part of a line instead of deleting a whole line, use an s/// command instead of a d command. As for escaping, you can escape a character to sed by preceding it with a backslash (\), which itself must be quoted or escaped to protect it from interpretation by the shell. Additionally, most regex metacharacters lose their special significance when they appear inside a character class, which I find to be a more legible way to include them in a pattern as literals. For example:
lastblock="./2.json"
echo "$lastblock" | sed 's/^[.]\///; s/[.]json$//'
That says to remove the literal characters ./ appearing at the beginning of the (any) line, and, separately, to remove the literal characters .json appearing at the end of the line.
Alternatively, if you want to modify only those lines that both start with ./ and end with .json then you can use a single s command with a capturing group and a backreference:
lastblock="./2.json"
echo "$lastblock" | sed 's/^[.]\/\(.*\)[.]json$/\1/'
That says that on lines that start with ./ and end with .json, capture everything between those two and replace the whole line with the captured part alone.
You can use another character like '#' when you want to avoid slashes.
You can remember a part that matches and use it in the replacement.
Use [.] avoiding the dot to be any character.
echo "$lastblock" | sed -r 's#[.]/(.*)[.]json#\1#'
Solution!
Just discovered today the tr command thanks to this legendary, unrelated answer.
When searching all over Google for how to exclude "." and "/", 100% of StackOverflow answers didn't helped.
So, to escape characters from the output of a command, just append this pipe:
| tr -d "{character-emoji-anything-you-want-to-exclude}"
So, a full working and simple sample:
echo "./2.json" | tr -d "/" | tr -d "." | tr -d "json"
And done!
If I run these commands from a script:
#my.sh
PWD=bla
sed 's/xxx/'$PWD'/'
...
$ ./my.sh
xxx
bla
it is fine.
But, if I run:
#my.sh
sed 's/xxx/'$PWD'/'
...
$ ./my.sh
$ sed: -e expression #1, char 8: Unknown option to `s'
I read in tutorials that to substitute environment variables from shell you need to stop, and 'out quote' the $varname part so that it is not substituted directly, which is what I did, and which works only if the variable is defined immediately before.
How can I get sed to recognize a $var as an environment variable as it is defined in the shell?
Your two examples look identical, which makes problems hard to diagnose. Potential problems:
You may need double quotes, as in sed 's/xxx/'"$PWD"'/'
$PWD may contain a slash, in which case you need to find a character not contained in $PWD to use as a delimiter.
To nail both issues at once, perhaps
sed 's#xxx#'"$PWD"'#'
In addition to Norman Ramsey's answer, I'd like to add that you can double-quote the entire string (which may make the statement more readable and less error prone).
So if you want to search for 'foo' and replace it with the content of $BAR, you can enclose the sed command in double-quotes.
sed 's/foo/$BAR/g'
sed "s/foo/$BAR/g"
In the first, $BAR will not expand correctly while in the second $BAR will expand correctly.
Another easy alternative:
Since $PWD will usually contain a slash /, use | instead of / for the sed statement:
sed -e "s|xxx|$PWD|"
You can use other characters besides "/" in substitution:
sed "s#$1#$2#g" -i FILE
一. bad way: change delimiter
sed 's/xxx/'"$PWD"'/'
sed 's:xxx:'"$PWD"':'
sed 's#xxx#'"$PWD"'#'
maybe those not the final answer,
you can not known what character will occur in $PWD, / : OR #.
if delimiter char in $PWD, they will break the expression
the good way is replace(escape) the special character in $PWD.
二. good way: escape delimiter
for example:
try to replace URL as $url (has : / in content)
x.com:80/aa/bb/aa.js
in string $tmp
URL
A. use / as delimiter
escape / as \/ in var (before use in sed expression)
## step 1: try escape
echo ${url//\//\\/}
x.com:80\/aa\/bb\/aa.js #escape fine
echo ${url//\//\/}
x.com:80/aa/bb/aa.js #escape not success
echo "${url//\//\/}"
x.com:80\/aa\/bb\/aa.js #escape fine, notice `"`
## step 2: do sed
echo $tmp | sed "s/URL/${url//\//\\/}/"
URL
echo $tmp | sed "s/URL/${url//\//\/}/"
URL
OR
B. use : as delimiter (more readable than /)
escape : as \: in var (before use in sed expression)
## step 1: try escape
echo ${url//:/\:}
x.com:80/aa/bb/aa.js #escape not success
echo "${url//:/\:}"
x.com\:80/aa/bb/aa.js #escape fine, notice `"`
## step 2: do sed
echo $tmp | sed "s:URL:${url//:/\:}:g"
x.com:80/aa/bb/aa.js
With your question edit, I see your problem. Let's say the current directory is /home/yourname ... in this case, your command below:
sed 's/xxx/'$PWD'/'
will be expanded to
sed `s/xxx//home/yourname//
which is not valid. You need to put a \ character in front of each / in your $PWD if you want to do this.
Actually, the simplest thing (in GNU sed, at least) is to use a different separator for the sed substitution (s) command. So, instead of s/pattern/'$mypath'/ being expanded to s/pattern//my/path/, which will of course confuse the s command, use s!pattern!'$mypath'!, which will be expanded to s!pattern!/my/path!. I’ve used the bang (!) character (or use anything you like) which avoids the usual, but-by-no-means-your-only-choice forward slash as the separator.
Dealing with VARIABLES within sed
[root#gislab00207 ldom]# echo domainname: None > /tmp/1.txt
[root#gislab00207 ldom]# cat /tmp/1.txt
domainname: None
[root#gislab00207 ldom]# echo ${DOMAIN_NAME}
dcsw-79-98vm.us.oracle.com
[root#gislab00207 ldom]# cat /tmp/1.txt | sed -e 's/domainname: None/domainname: ${DOMAIN_NAME}/g'
--- Below is the result -- very funny.
domainname: ${DOMAIN_NAME}
--- You need to single quote your variable like this ...
[root#gislab00207 ldom]# cat /tmp/1.txt | sed -e 's/domainname: None/domainname: '${DOMAIN_NAME}'/g'
--- The right result is below
domainname: dcsw-79-98vm.us.oracle.com
VAR=8675309
echo "abcde:jhdfj$jhbsfiy/.hghi$jh:12345:dgve::" |\
sed 's/:[0-9]*:/:'$VAR':/1'
where VAR contains what you want to replace the field with
I had similar problem, I had a list and I have to build a SQL script based on template (that contained #INPUT# as element to replace):
for i in LIST
do
awk "sub(/\#INPUT\#/,\"${i}\");" template.sql >> output
done
If your replacement string may contain other sed control characters, then a two-step substitution (first escaping the replacement string) may be what you want:
PWD='/a\1&b$_' # these are problematic for sed
PWD_ESC=$(printf '%s\n' "$PWD" | sed -e 's/[\/&]/\\&/g')
echo 'xxx' | sed "s/xxx/$PWD_ESC/" # now this works as expected
for me to replace some text against the value of an environment variable in a file with sed works only with quota as the following:
sed -i 's/original_value/'"$MY_ENVIRNONMENT_VARIABLE"'/g' myfile.txt
BUT when the value of MY_ENVIRONMENT_VARIABLE contains a URL (ie https://andreas.gr) then the above was not working.
THEN use different delimiter:
sed -i "s|original_value|$MY_ENVIRNONMENT_VARIABLE|g" myfile.txt
We are receiving a file that is delimited into rows with the \(newline) and columns with the \(tab) character.
When there is a manual newline present in one of the "fields" of the file, it comes in as a special newline with two backslashes (\\newline).
To remove the special tabs \(tab), we are using this sed command, which works correctly:
sed "s/$(printf '\\\\\t')/ /g"
The corresponding command for newlines, however does not:
sed "s/$(printf '\\\\\n')/ /g"
It does not remove the \n, only the backslash before it. Is there special handling that needs to be done to remove \(newline)?
Clarification: normal newlines are formatted like this:
\(newline)
Wheras the special characters that need removal are
\\(newline)
Here you go:
echo -e 'hello\\\nthere' | perl -ne 's/\\\n/ /; print'
It would be difficult (but probably possible) to do this in sed, because sed processes input line by line, and your data is broken into multiple lines. This perl one-liner processes the input line by line, and since it treats the newline character as part of the line, it can perform a substitution with space, which I think has the effect that you want.
Or if you prefer awk:
echo -e 'hello\\\nthere' | awk '{ if (gsub(/\\$/, " ")) printf; else print }'
At first I suspected your "special newline" character is just the string \\n like in the output of this command:
echo 'hello\\nthere'
You can replace the string \\n with a space like this:
echo 'hello\\nthere' | sed -e 's/\\\\n/ /g'
You can use tr (translate) command as well to do this, like
tr '\n' ' ' < inputfile.txt
EdIT: In that case use it like
tr '\\\n' ' ' < inputfile.txt
I want to pass this command in my script:
sed -n -e "/Next</a></p>/,/Next</a></p>/ p" file.txt
This command (should) extract all text between the two matched patterns, which are both Next</a></p> in my case. However when I run my script I keep getting errors. I've tried:
sed -n -e "/Next\<\/a\>\<\/p\>/,/Next<\/a\>\<\/p>/ p" file.txt with no luck.
I believe the generic pattern for this command is this:
sed -n -e "/pattern1/,/pattern2/ p" file.txt
I can't get it working for Next</a></p> though and I'm guessing it has something to do with the special characters I am encasing. Is there any way to pass Next</a></p> in the sed command? Thanks in advance guys! This community is awesome!
You don't need to use / as a regular expression delimiter. Using a different character will make quoting issues slightly easier. The syntax is
\cregexc
where c can be any character (other than \) that you don't use in the regex. In this case, : might be a good choice:
sed -n -e '\:Next</a></p>:,\:Next</a></p>: p' file.txt
Note that I changed " to ' because inside double quotes, \ will be interpreted by bash as an escape character, whereas inside single quotes \ is just treated as a regular character. Consequently, you could have written the version with escaped slashes like this:
sed -n -e '/Next<\/a><\/p>/,/Next<\/a><\/p>/ p' file.txt
but I think the version with colons is (slightly) easier to read.
You need to escape the forward slashes inside the regular expressions with a \, since the forward slashes serve as delimiters for the regexes
sed -n -e '/Next<\/a><\/p>/,/Next<\/a><\/p>/p' file.txt