Replacing characters in each line on a file in linux

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I have a file with different word in each line. My goal is to replace the first character to a capital letter and replace the 3rd character to "#".

For example:football will be exchanged to -> Foo#ball

I tried thinking about using awk and sed.It didn't help me since (to my knowledge) sed needs an exact character input and awk can print the desired character but not change it.

With GNU sed and two s commands:

echo 'football' | sed -E 's/(.)/\U\1/; s/(...)./\1#/'

Output:

Foo#ball

See: 3.3 The s Command, 5.7 Back-references and Subexpressions and 5.9.2 Upper/Lower case conversion

How to Use sed to Find and Replace String in Files, macOS uses the BSD version and most Linux distributions come with GNU sed By default, sed reads the file line by line and changes only the first If you want to find and replace a string that contains the delimiter character� I have a file with different word in each line. My goal is to replace the first character to a capital letter and replace the 3rd character to "#". For example:football will be exchanged to -> Foo

This might work for you (GNU sed):

sed 's/\(...\)./\u\1#/' file

Replace last characters in each line, I want to replace 150th character of all the lines in a file using sed or awk searched the forums but didn't find exact answer | The UNIX and Linux Forums. sed -i 's+regex+new-text+g' file.txt The above replace all occurrences of characters in word1 in the pattern space with the corresponding characters from word2. Examples that use sed to find and replace. Let us create a text file called hello.txt as follows: $ cat hello.txt The is a test file created by nixCrft for demo purpose. foo is good. Foo is nice.

With bash you can use parameter expansions alone to accomplish the task. For example, if you read each line into the variable line, you can do:

line="${line^}"                # change football to Football (capitalize 1st char)
line="${line:0:3}#${line:4}"   # make 4th character '#'

Example Input File

$ cat file
football
soccer
baseball

Example Use/Output

$ while read -r line; do line="${line^}"; echo "${line:0:3}#${line:4}"; done < file
Foo#ball
Soc#er
Bas#ball

While shell is typically slower, when use is limited to builtins, it doesn't fall too far behind.

(note: your question says 3rd character, but your example replaces the 4th character with '#')

Replace nth position character of all the lines in file, replace end of all lines in a file with '||chr( except last line I am able to do the entire file using sed -e s/^/\'/g -e s/$/\'\|\|chr\(/g "$file" > newfile.txt but am not yet You learned how to remove the last character from text file and each line, including shell variables on Linux and Unix-like systems. Of course, we can use the awk command, cut command, Perl/Python and so on. However, I prefer to use sed as it is installed by default on all systems, and it is made for this kind of job.

With GNU awk for the 3rd arg to match():

$ echo 'football' | awk 'match($0,/(.)(..).(.*)/,a){$0=toupper(a[1]) a[2] "#" a[3]} 1'
Foo#ball

sed replace range of characters in each line, Replace all instances of a text in a particular line of a file using 'g' option Output : The file path, '/home/ubuntu/code/perl/add.pl' is provided as input in the `sed` The following `sed` command will replace each tab (\t) character by four space� tr Command - Translate, Replace or Remove Specific Characters The tr command is designed to translate, squeeze and/or delete characters in standard input (stdin) and write them to standard output (stdout). It is often used on the command line for string manipulation in a pipeline.

Cyrus' or Potong's answers are the preferred ones. (For Linux or systems with GNU sed because of \U or \u.)

This is just an additional solution with awk because you mentioned it and used also awk tag:

$ echo 'football'|awk '{a=substr($0,1,1);b=substr($0,2,2);c=substr($0,5);print toupper(a)b"#"c}'
Foo#ball

This is a most simple solution without RegEx. It will also work on non-GNU awk.

50 `sed` Command Examples – Linux Hint, txt is used, it's basically shell's way of reading file line by line. See this for reference. AWK. AWK, being a text processing utility, is quite� (.) - capture single character (the first character on line).{29} - next 29 characters on line (.*) - capture remaining characters on the line hoohaa - replacement text If a line contains less than 30 characters, it remains unaffected

Find and replace text within a file using commands, The procedure to change the text in files under Linux/Unix using sed: The above replace all occurrences of characters in word1 in the pattern In this example only find word 'love' and replace it with 'sick' if line content a� The cut command is used in Linux and Unix systems to cut parts and sections from each line of a file and write the result to standard output. It can be used to cut parts of a line by byte position, character and field (delimiter). In this tutorial, we learn Linux cut command with some practical

How to use sed to find and replace text in files in Linux / Unix shell , It is perfect for removing/deleting the last character and perform other options on your files or shell variables. ADVERTISEMENTS. sed remove�

sed remove last character from each line on Linux / Unix, replace # with ' ' ( space ) to add space in front of each line: $ sed 's/^/ /' file.txt add character at the beginning of each line. Redirect the output�

Comments
  • It is hard to say what is wrong with your code because you did not provide it or the errors you encountered. Also see How to create a Minimal, Complete, and Verifiable example.
  • sed needs an exact character input? Completely the opposite, sed cannot operate on an exact character input - see stackoverflow.com/q/29613304/1745001 for the hoops you have to jump through to make sed act as if it were using literal strings.
  • The read alone will make it extremely slow compared to a sed or awk solution, see unix.stackexchange.com/q/169716/133219. Always quote your variables unless you need to do something that requires them to be unquoted - see mywiki.wooledge.org/Quotes. In this case even if we assume there's no spaces in the input you'd get unfortunate results if the input contained globbing chars that just happened to match local file names.
  • Yes, this only does about 100,000 lines per-second (with SSD), so if your file is millions, you will want something faster. If you are dealing with 1000 lines or less, it's in the noise. Agree on the quoting, that was just omitted due to the one-word input -- but it should be there for generalization.
  • On my machine it takes 4.81 secs for 100,000 lines :-). FWIW potong's GNU sed solution (unsurprisingly since this is what sed is best for) took 0.17 secs while my GNU awk one took 0.98 secs and reichharts POSIX awk one only took 0.22 secs. Agreed on the "if you're dealing with 1000 lines or less..." BUT then you'd be looking for some other reason to use it over sed or awk. I'm only commenting because you said when use is limited to builtins, it doesn't fall too far behind as it does still fall very far behind.
  • I used /usr/lib/dict/words for the test 305089-words (3.481s total). I'm not saying its faster, you know that. The "not too far behind" could better be expressed as "not near as bad as calling an additional utility inside the loop". awk solution (1.833s total) same file, run in subshell redirected to /dev/null.
  • Thanks. In this case it's kinda overkill though so if this is really all that needs to be done then in reality I'd have to go with @potongs if you have GNU tools and if you don't then @reichharts.
  • Let me phrase it differently :-) : AFAIK I am not using any "GNU extension". Thus the solution should be most compatible.
  • Thanks. First of all I was not sure about the compatibility and second I was not sure about the (english) language. :-) Updated it.
  • "different word in each line": That means that only one word is used per line. Your solution also works on multiple words in one line.
  • True. Well, it works also if there is just one word in each line. :)