Hi I'm new to unix and trying to make a script that removes punctuation from user input using SED. But it isn't working.
read -p "Please enter a word or sentence: " word
sed -n 's/[^a-zA-Z ]//g' $word
if i enter abcd.,abcd it will give me an error
"sed: can't read abcd,.abcd: No such file or directory"
So I guess that means it is treating the variable $word as a file instead of a string that I want it to process.
How would I fix this?
sed treat argument as input-file.
Try following instead:
echo "$word" | sed -n 's/[^a-z]//ig'
This might work for you (bash):
sed 's/[^a-zA-Z ]//g' <<<"$word"
This utilizes the here-string in bash.
Related
File Content
abab102
cdcd103
efef105
I want the username and id separated. Here, abab is user and 102 is id.
I use the command
sed 's/\([a-z]\)\{4\}\([0-9]\)\{3\}/Username:\1 ID:\2/' file.txt
Get this
Username:b ID:2
Username:d ID:3
Username:f ID:5
But I am expecting
Username:abab ID:102
Username:cdcd ID:103
Username:efef ID:105
But using the command
sed -e 's/\([a-z]\)\{4\}/Username:&/' -e 's/\([0-9]\)\{3\}/ID:&/' file2.txt
Output
Username:ababID:102
Username:cdcdID:103
Username:efefID:105
This output is close to what I need, but still I am expecting a blank space between Username:abab ID:102.
I want to know why \1 or \2 is not working here.
\([a-z]\) - between ( ) is one letter. If you repeat the \(\) group, back reference goes to the last matched expression. Put all the repetition inside.
's/\([a-z]\{4\}\)\([0-9]\{3\}\)/Username:\1 ID:\2/'
Ugh, simpler with extended:
sed -E 's/([a-z]{4})([0-9]{3})/Username:\1 ID:\2/'
Using sed
$ sed -E 's/[[:alpha:]]{4}/Username:& ID:/' input_file
Username:abab ID:102
Username:cdcd ID:103
Username:efef ID:105
I would like to use sed to remove all occurances of this line if and only if it is this
<ab></ab>
If this line, I would not want to delete it
<ab>keyword</ab>
My attempt that's not working:
sed '/<ab></ab>/d'
Thanks for any insight. I'm not sure what's wrong as I should not have to escape anything?
I'm using a shell script named temp to execute this. My command is this:
cat foobar.html | ./temp
This is my temp shell script:
#!/bin/sh
sed -e '/td/!d' | sed '/<ab></ab>/d'
It looks like we have a couple of problems here. The first is with the / in the close-tag. sed uses this to delimit different parts of the command. Fortunately, all we have to do is escape it with \. Try:
sed '/<ab><\/ab>/d'
Here's an example on my machine:
$ cat test
<ab></ab>
<ab></ab>
<ab>test</ab>
$ sed '/<ab><\/ab>/d' test
<ab>test</ab>
$
The other problem is that I'm not sure what the purpose of sed -e '/td/!d' is. In it's default operating mode, you don't need to tell it not to delete something; just tell it exactly what you want to delete.
So, to do this on a file called input.html:
sed '/<ab><\/ab>/d' input.html
Or, to edit the file in-place, you can just do:
sed -i -e '/<ab><\/ab>/d' input.html
Additionally, sed lets you use any character you want as a delimiter; you don't have to use /. So if you'd prefer not to escape your input, you can do:
sed '\#<ab></ab>#d' input.html
Edit
In the comments, you mentioned wanting to delete lines that only contain </ab> and nothing else. To do that, you need to do what's called anchoring the match. The ^ character represents the beginning of the line for anchoring, and $ represents the end of the line.
sed '/^<\/ab>$/d' input.html
This will only match a line that contains (literally) </ab> and nothing else at all, and delete the line. If you want to match lines that contain whitespace too, but no text other than </ab>:
sed '/^[[:blank:]]*<\/ab>[[:blank:]]*$/d' input.html
[[:blank:]]* matches "0 or more whitespace characters" and is called a "POSIX bracket expression".
I'm trying to insert into a text file the string cd $var at the second line using sed, but it doesn't seem to work. I'm using the syntax for inserting a line at a specific line in a file,
sed -i '2icd $var' FILE
The format of which was found as the response to this question:
Insert a line at specific line number with sed or awk
My best guess is that sed is interpreting the command literally and evaluating it instead of copying it in. However, all of my attempts at forcing it to be evaluated simply as a string have failed. My attempts so far:
sed -i '2i\cd $var' FILE
sed -i '2i\cd \$var' FILE
sed -i "2i'cd $var'" FILE
and
Line='cd $var'
sed -i "2i$Line" FILE
I was fairly sure this last attempt would succeed, due to the hard quotes, but it still failed.
In fact, this also failed,
sed -i '2icd' FILE
Yet this succeeded (Just to confirm the general format):
sed -i '2ic' FILE
Just to be clear, all 5 of the failed attempts yielded the same error: A blank line was inserted at the desired location.
sed -i "2 i\\
$var" file
need a escape NewLine normaly after the i and depending the OS/sed a space before and/or after the i also. Finaly, with double quote, escape the \
I have created a file named "asd.txt" on a UNIX based system.
I added four lines by using echo command.
Now, I would like to change the first line of this file.
I am not allowed to use any text editors, such as vi.
I have to do this by using only command line. Can anyone help?
Thanks.
Here is how you could do it with sed.
sed '1 s/search/replace/' asd.txt
If you are feeling up to it and have GNU sed, use the -i switch to do it in place.
If you want to replace the entire first line how about doing this?
echo "Here is my new first line" && sed '1d' asd.txt
For both of these commands you can redirect the output to a new file using the > operator.
#!/bin/bash
cat <(echo "Replacement") <(tail -n +2 foo.txt)
I'm trying to do the opposite of this question, replacing Unix line endings with Windows line endings, so that I can use SQL Server bcp over samba to import the file. I have sed installed but not dos2unix. I tried reversing the examples but to no avail.
Here's the command I'm using.
sed -e 's/\n/\r\n/g' myfile
I executed this and then ran od -c myfile, expecting to see \r\n where there used to be \n. But there all still \n. (Or at least they appear to be. The output of od overflows my screen buffer, so I don't get to see the beginning of the file).
I haven't been able to figure out what I'm doing wrong. Any suggestions?
When faced with this, I use a simple perl one-liner:
perl -pi -e 's/\n/\r\n/' filename
because sed behavior varies, and I know this works.
What is the problem with getting dos2unix onto the machine?
What is the platform you are working with?
Do you have GNU sed or regular non-GNU sed?
On Solaris, /usr/bin/sed requires:
sed 's/$/^M/'
where I entered the '^M' by typing controlV controlM. The '$' matches at the end of the line, and replaces the end of line with the control-M. You can script that, too.
Mechanisms expecting sed to expand '\r' or '\\r' to control-M are going to be platform-specific, at best.
You don't need the -e option.
$ matches the endline character. This sed command will insert a \r character before the end of line:
sed 's/$/\r/' myfile
Just adding a \r (aka ^M, see Jonathan Leffler's answer) in front of \n is not safe because the file might have mixed mode EOL, so then you risk ending up with some lines becomming \r\r\n. The safe thing to do is first remove all '\r' characters, and then insert (a single) \r before \n.
#!/bin/sh
sed 's/^M//g' ${1+"$#"} | sed 's/$/^M/'
Updated to use ^M.
sed 's/\([^^M]\)$/\0^M/' your_file
This makes sure you only insert a \r when there is no \r before \n. This worked for me.
Try using:
echo " this is output" > input
sed 's/$/\r/g' input |od -c
Maybe if you try it this way
cat myfile | sed 's/\n/\r\n/g' > myfile.win
will work, from my understanding your just making the replacements to the console output, you need to redirect output to a file, in this case myfile.win, then you could just rename it to whatever you want. The whole script would be (running inside a directory full of this kind of files):
#!/bin/bash
for file in $(find . -type f -name '*')
do
cat $file | sed 's/\n/\r\n/g' > $file.new
mv -f $file.new $file
done