I've researched other questions on here, but haven't really found one that works for me. I'm trying to select a specific line from a file and replace a string on that line with another string. So I have a file named my_course. I'm trying to modify a line in my_course that starts with "123". on that line I want to replace the string "0," with "1,". Help?
One possibility would be to use sed:
sed '/^123/ s/0/1/' my_course
In the first /../ part you just have to specify the pattern you are looking for ^123 for a line starting with 123.
In the s/from/to/ part you have specify the substitution to be performed.
Note that by default after substitution the file will be written to stdout. You might want to:
redirect the output using ... > my_new_course
perform the substitution "in place" using the -e switch to sed
If you are using the destructive in place variant you might want to use -iEXTENSION in addition to keep a copy with the given EXTENSION of the original version in case something goes wrong.
EDIT:
To match the desired lined with a prefix stored in a variable you have to enclose the sed script with double quotes " as using single qoutes ' will prevent variable expansion:
sed "/^$input/ s/0/1/" my_course
Have you tried this:
sed -e '[line]s/old_string/new_string/' my_course
PS: the [ ] shouldn't be used, is there just to make it clear that you should put the number right before the "s".
Cheers!
In fact, the -e in this case is not necessary, I can write just
sed '<line number>s/<old string>/<new string>/' my_course
This is what worked for me on Fedora 36, GNU bash, version 5.2.15(1)-release (x86_64-redhat-linux-gnu):
sed -i '1129s/additional/extra/' en-US/Design.xml
I know you said you couldn't use line numbers; I don't know how to address that part, but this replaced "additional" with "extra" on line 1129 of that file.
Related
So I think I've cracked the regex but just can't crack how to get sed to make the changes. I have a variable which is this:
MAKEVAR = EPICS_BASE=$CI_PROJECT_DIR/3.16/base IPAC=$CI_PROJECT_DIR/3.16/support/ipac SNCSEQ=$CI_PROJECT_DIR/3.16/support/seq
(All one line). But I want to delete the particular section defining IPAC so my regex looks like this:
(IPAC.+\s)
I know from using this tool that that should be correct:
https://www.regextester.com/98103
However when I run different iterations of trying out sed like:
sed 's/(IPAC.+\s)/\&/g' <<< "$MAKEVAR"
And then echo out MAKEVAR, the IPAC section still exists.
How can I update a particular section of text in a shell variable to remove a section beginning with IPAC up until the next space?
Thanks in advance
regextester (or any other online tool) is a great way to verify that a regexp works in that online tool. Unfortunately that doesn't mean it'll work in any given command-line tool. In particular your regexp includes \s which is specific to PCREs and some GNU tools, and uses (...) to delineate capture groups but that's only used in EREs and PCREs, not BREs such as sed supports by default where you'd have to use \(...\), and your replacement text is using '&' which is telling sed you want to replace the string that matches the regexp with a literal \& when in fact you just want to remove it.
This is how to do what I think you're trying to do using any sed:
$ sed 's/IPAC[^ ]* //' <<< "$MAKEVAR"
EPICS_BASE=$CI_PROJECT_DIR/3.16/base SNCSEQ=$CI_PROJECT_DIR/3.16/support/seq
Nevermind, found a workaround:
MAKEVAR=$(sed -E 's/(IPAC.+ipac)//' <<<"$MAKEVAR")
Use a shorter
MAKEVAR=$(sed 's/IPAC.*ipac//' <<< "$MAKEVAR")
IPAC.*ipac matches all the way from first IPAC to last ipac. The matched text is removed from the text.
Before to write, of course I read many other similar cases. Example I used #!/bin/bash instead of #!/bin/sh
I have a very simple script that reads lines from a template file and wants to replace some keywords with real data. Example the string <NAME> will be replaced with a real name. In the example I want to replace it with the word Giuseppe. I tried 2 solutions but they don't work.
#!/bin/bash
#read the template and change variable information
while read LINE
do
sed 'LINE/<NAME>/Giuseppe' #error: sed: -e expression #1, char 2: extra characters after command
${LINE/<NAME>/Giuseppe} #error: WORD(*) command not found
done < template_mail.txt
(*) WORD is the first word found in the line
I am sorry if the question is too basic, but I cannot see the error and the error message is not helping.
EDIT1:
The input file should not be changed, i want to use it for every mail. Every time i read it, i will change with a different name according to the receiver.
EDIT2:
Thanks your answers i am closer to the solution. My example was a simplified case, but i want to change also other data. I want to do multiple substitutions to the same string, but BASH allows me only to make one substitution. In all programming languages i used, i was able to substitute from a string, but BASH makes this very difficult for me. The following lines don't work:
CUSTOM_MAIL=$(sed 's/<NAME>/Giuseppe/' template_mail.txt) # from file it's ok
CUSTOM_MAIL=$(sed 's/<VALUE>/30/' CUSTOM_MAIL) # from variable doesn't work
I want to modify CUSTOM_MAIL a few times in order to include a few real informations.
CUSTOM_MAIL=$(sed 's/<VALUE1>/value1/' template_mail.txt)
${CUSTOM_MAIL/'<VALUE2>'/'value2'}
${CUSTOM_MAIL/'<VALUE3>'/'value3'}
${CUSTOM_MAIL/'<VALUE4>'/'value4'}
What's the way?
No need to do the loop manually. sed command itself runs the expression on each line of provided file:
sed 's/<NAME>/Giuseppe/' template_mail.txt > output_file.txt
You might need g modifier if there are more appearances of the <NAME> string on one line: s/<NAME>/Giuseppe/g
I have a file with the following entries:
folder1/a_b.csv folder1/generated/
folder2/folder3/a_b1.csv folder12/generated/
folder4/b_c.csv folder123/generated/
folder5/d.csv folder1/new_folder/generated/
folder6/12.csv folder/anotherfolder/morefolder/evenmorefolder/generated/
I want to copy the csv file name from each line, paste them at the end of that line and append it with ".org". Hence, the changed file would look like
folder1/a_b.csv folder1/generated/a_b.csv.org
folder2/folder3/a_b1.csv folder12/generated/a_b1.csv.org
folder4/b_c.csv folder123/generated/b_c.csv.org
folder5/d.csv folder1/new_folder/generated/d.csv.org
folder6/12.csv folder/anotherfolder/morefolder/evenmorefolder/generated/12.csv.org
Basically, I am looking for a command in vim or sed using which I can search a pattern in each line and append it at the end of that line. Is it possible?
Thanks in advance.
Vim
Here's how to do this in Vim:
:%s/\([^/]*\.csv\)\( .*\)/&\1.org/
This global (:%) substitution matches the filename (characters that don't contain /, ending in .csv), and captures \(...\) it. It then matches the rest of the line, and captures that, too.
As a replacement, first keep the original match & (or \0), then append the first capture (\1) with the additional suffix.
sed
Though the regular expression syntax is somewhat different than in Vim, the identical expression can be used with sed:
sed -e 's/\([^/]*\.csv\)\( .*\)/&\1.org/' input
Alternatives
It looks like you want to do file renaming in batches. On Linux, the mmv command-line tool is well suited for that; you'll probably find many similar tools on the web, too.
This might work for you (GNU sed):
sed -r 's|/([^ ]*) .*|&\1.org|' file
My file has a lot of line breaks, like this:
This is a line.
This is another line.
I would like to remove these, but only in cases where the first line ends with }, e.g.:
\macro{This is a line.}
This is another line.
That should become:
\macro{This is a line.}This is another line.
How can I remove the line breaks in this situation?
This is what I figured out:
$ sed -n '/}$/{h;:a;n;/^$\|}$/{H;$!ba};H;g;s#}\n*#}#g};p' input.txt
The idea behind is:
Accumulate all continuous empty lines and lines endswith '}'
Substitute }\n* with }
Last line needs special consideration.
You can just use an editor that support regular expressions and do a replace in your file. Replace:
}$\n\n
with
}
If you need to do it programmatically, the same principle applies (i.e. using regex for string replacement) but the actual answer will obviously depend on language/environment.
This might work for you:
sed '$!N;s/}\n$/}/;P;D' file
if there is white space involved, try:
sed '$!N;s/}\s*\n\s*$/}/;P;D' file
or more formally:
sed '$!N;s/}[[:space:]]*\n[[:space:]]*$/}/;P;D' file
i have a template, with a var LINK
and a data file, links.txt, with one url per line
how in bash i can substitute LINK with the content of links.txt?
if i do
#!/bin/bash
LINKS=$(cat links.txt)
sed "s/LINKS/$LINK/g" template.xml
two problem:
$LINKS has the content of links.txt without newline
sed: 1: "s/LINKS/http://test ...": bad flag in substitute command: '/'
sed is not escaping the // in the links.txt file
thanks
Use some better language instead. I'd write a solution for bash + awk... but that's simply too much effort to go into. (See http://www.gnu.org/manual/gawk/gawk.html#Getline_002fVariable_002fFile if you really want to do that)
Just use any language where you don't have to mix control and content text. For example in python:
#!/usr/bin/env python
links = open('links.txt').read()
template = open('template.xml').read()
print template.replace('LINKS', links)
Watch out if you're trying to force sed solution with some other separator - you'll get into the same problems unless you find something disallowed in urls (but are you verifying that?) If you don't, you already have another problem - links can contain < and > and break your xml.
You can do this using ed:
ed template.xml <<EOF
/LINKS/d
.r links.txt
w output.txt
EOF
The first command will go to the line
containing LINKS and delete it.
The second line will insert the
contents of links.txt on the current
line.
The third command will write the file
to output.txt (if you omit output.txt
the edits will be saved to
template.xml).
Try running sed twice. On the first run, replace / with \/. The second run will be the same as what you currently have.
The character following the 's' in the sed command ends up the separator, so you'll want to use a character that is not present in the value of $LINK. For example, you could try a comma:
sed "s,LINKS,${LINK}\n,g" template.xml
Note that I also added a \n to add an additional newline.
Another option is to escape the forward slashes in $LINK, possibly using sed. If you don't have guarantees about the characters in $LINK, this may be safer.