I need to remove the character : from a file. Ex: I have numbers in the following format:
b3:07:4d
I want them to be like:
b3074d
I am using the following command:
grep ':' source.txt | sed -e 's/://' > des.txt
I am new to Linux. The file is quite big & I want to make sure I'm using the write command.
You can do without the grep:
sed -e 's/://g' source.txt > des.txt
The -i option edits the file in place.
sed -i 's/://' source.txt
the first part isn't right as it'll completely omit lines which don't contain :
below is untested but should be right. The g at end of the regex is for global, means it should get them all.
sed -e 's/://g' source.txt > out.txt
updated to better syntax from Jon Lin's answer but you still want the /g I would think
Related
Specify the command that removes multiple spaces from a text file, leaving a single space in their place. Extra requirements : Original file to be modified.
Managed to pull out those 3 commands:
awk '{$2=$2};1' filename.txt
tr -s '[:space:]' < filename.txt > filename.new && mv filename.new filename.txt
sed -i 's/\s\+/ /g' filename.txt
Not sure if using a 'temporary file' is the best way to do the trick. Is there any more efficient way to do the problem ? Doesn't matter if it is tr / sed / awk or anything else, you can post all of them.
Example input:
I'm just giving spaces
Output :
I'm just giving spaces
Edit: Still looking for more answers
I'd use ed over the non-standard sed -i (And non-portable RE in your example) if you want to alter the original file:
printf "%s\n" '1,$s/[[:space:]]\{2,\}/ /g' w | ed -s filename.txt
or with perl:
perl -pi -e 's/\s{2,}/ /g' filename.txt
The {2,} regular expression construct (\{2,\} for POSIX Basic Regular Expressions like sed and ed use) matches 2 or more of the previous token.
Both of these match any whitespace characters, not just space, because that's how your examples work. If the goal is to only compress multiple spaces, not spaces + tabs, switch out the [[:space:]] and \s for just a single space.
(Anything that modifies a file "in place", be it ed, sed -i, perl -i, or a regular editor, has a good chance that it's going to be using a temporary file under the hood, by the way. They just handle it for you so you don't have to do it manually like with your tr example.)
I am trying to replace string into number from the file
So, I have variable &FLOW which need to change to 001, ex :
cat file.txt
This is file ' PISP &FLOW'
PISD.DATA.CYCLE&FLOW..ONE
desired output
This is file ' PISP 001'
PISD.DATA.CYCLE001.ONE
I tried below commands in a script :
for item in file.txt
do
sed 's/\&FLOW/\./001/g' $item
sed 's/\&FLOW/001/g' $item
done
It is giving error. The second sed command is working, but I need to run first the beginning sed command otherwise after running first the second sed command, it would ignore the beginning sed command.
Any help would be appreciated!
Use a single sed command and use -i to actually modify the file contents and you need to pass file.txt as the input for the sed command:
sed -i 's/&FLOW\.\{0,1\}/001/g' file.txt
See the online demo. If you are using it in Mac OS, you need sed -i '' 's/&FLOW\.\{0,1\}/001/g' file.txt. Also see sed edit file in place.
Pattern details
It is a POSIX BRE compliant pattern matching
&FLOW - a literal &FLOW substring
\.\{0,1\} - 0 or 1 occurrence of a . char.
try this:
for item in file.txt
do
sed 's/\&FLOW\./001/g' $item
sed 's/\&FLOW/001/g' $item
done
You had a redundant / in after FLOW
This might also work:
sed -i 's/\&FLOW[\.]?/001/g' file.txt
I am attempting to use sed to delete a line, read from user input, from a file whose name is stored in a variable. Right now all sed does is print the line and nothing else.
This is a code snippet of the command I am using:
FILE="/home/devosion/scripts/files/todo.db"
read DELETELINE
sed -e "$DELETELINE"'d' "$FILE"
Is there something I am missing here?
Edit: Switching out the -e option with -i fixed my woes!
You need to delimit the search.
#!/bin/bash
read -r Line
sed "/$Line/d" file
Will delete any line containing the typed input.
Bear in mind that sed matches on regex though and any special characters will be seen as such.
For example searching for 1* will actually delete lines containing any number of 1's not an actual 1 and a star.
Also bear in mind that when the variable expands, it cannot contain the delimiters or the command will break or have unexpexted results.
For example if "$Line" contained "/hello" then the sed command will fail with
sed: -e expression #1, char 4: extra characters after command.
You can either escape the / in this case or use different delimiters.
Personally i would use awk for this
awk -vLine="$Line" '!index($0,Line)' file
Which searches for an exact string and has none of the drawbacks of the sed command.
You might have success with grep instead of sed
read -p "Enter a regex to remove lines: " filter
grep -v "$filter" "$file"
Storing in-place is a little more work:
tmp=$(mktemp)
grep -v "$filter" "$file" > "$tmp" && mv "$tmp" "$file"
or, with sponge (apt install moreutils)
grep -v "$filter" "$file" | sponge "$file"
Note: try to get out of the habit of using ALLCAPSVARS: one day you'll accidentally use PATH=... and then wonder why your script is broken.
I found this, it allows for a range deletion with variables:
#!/bin/bash
lastline=$(whatever you need to do to find the last line)` //or any variation
lines="1,$lastline"
sed -i "$lines"'d' yourfile
keeps it all one util.
Please try this :
sed -i "${DELETELINE}d" $FILE
$ cat example.txt
Yields:
example
test
example
I want to remove 'test' string from this file.
$ grep -v test example.txt > example.txt
$ cat example.txt
$
The below works, but I have a feeling there is a better way!
$ grep -v test example.txt > example.txt.tmp;mv example.txt.tmp example.txt
$ cat example.txt
example
example
Worth noting that this is going to be on a file with over 10,000 lines.
Cheers
You could use sed,
sed -i '/test/d' example.txt
-i saves the changes made to that file. so you don't need to use a redirection operator.
-i[SUFFIX], --in-place[=SUFFIX]
edit files in place (makes backup if SUFFIX supplied)
You're doing it the right way but use an && before the mv to make sure the grep succeeded or you'll zap your original file:
grep -F -v test example.txt > example.txt.tmp && mv example.txt.tmp example.txt
I also added the -F options since you said you want to remove a string, not a regexp.
You COULD use sed -i but then you need to worry about figuring out and/or escaping sed delimiters and sed does not support searching for strings so you'd need to try to escape every possible combination of regexp characters in your search string to try to make sed treat them as literal chars (a process you CANNOT automate due to the position-sensitive nature of regexp chars) and all it'd save you is manually naming your tmp file since sed uses one internally anyway.
Oh, one other option - you could use GNU awk 4.* with "inplace editing". It also uses a tmp file internally like sed does but it does support string operations so you don't need to try to escape RE metacharacters and it doesn't have delimiters as part of the syntax to worry about:
awk -i inplace -v rmv="test" '!index($0,rmv)' example.txt
Any grep/sed/awk solution will run the in blink of an eye on a 10,000 line file.
Say for instance I'm searching a line that is like this:
Color asdf
and I use grep to find that line, like grep asdf file.txt
How would I then display Color? Learning linux is hard.
With the command line tool sed you can replace stings by using regular expressions:
echo "Color asdf" | sed 's/\([^ ]*\).*/\1/'
This part: \([^ ]*\).* is a regular expresion. The first part of the regex: [^ ]*, matches any character except a space as many times as possible and what's between the \( and \) is being captured in the variable \1. Then you also match the remaining part of the string with .* and replace all of that with only the first word which was captured by \([^ ]*\) by using \1 in the replace part of the sed command.
Here some more info about sed:
http://linux.about.com/od/commands/a/Example-Uses-Of-Sed-Cmdsedxa.htm
You could use sed:
sed -n 's/[[:space:]][[:space:]]*asdf$//p' file.txt
Details:
The -n option tells sed not to print the pattern space automatically. Basically, it doesn't output anything unless you tell it to.
The s command of sed replaces text. Here, if a line ends with asdf, preceded by at least one whitespace character, we replace all of that with nothing and then print the line (notice the p flag at the end of the s command). The printing is only done if something was actually replaced. More information about the s command can be found e. g. in the GNU sed manual.
Edit for clarity: When using single quotes, parameter expansion does not work and thus, variables won't be replaced. To use variables, use double quotes:
search=asdf
sed -n "s/[[:space:]][[:space:]]*${search}\$//p" file.txt
If you'd really like to use grep here, you could pipe the output from grep into cut:
grep -h asdf *.txt | cut -s -d -f 1
Note that there have to be two spaces after the -d option to cut - the first tells cut to use a blank as the field delimiter (I'm assuming your fields are blank-delimited rather than tab-delimited), while the second separates the -d option from the following option (-f).
But, yeah, sed or awk are probably your friends here... :-)
you can color pattern in the line using grep
grep --colour -o 'asdf' file.txt
edit: the -o option will print only the patterns