How can I remove the last character of a file in unix?

by

A simpler approach (outputs to stdout, doesn’t update the input file):

sed '$ s/.$//' somefile

  • $ is a Sed address that matches the last input line only, thus causing the following function call (s/.$//) to be executed on the last line only.

  • s/.$// replaces the last character on the (in this case last) line with an empty string; i.e., effectively removes the last char. (before the newline) on the line.
    . matches any character on the line, and following it with $ anchors the match to the end of the line; note how the use of $ in this regular expression is conceptually related, but technically distinct from the previous use of $ as a Sed address.

  • Example with stdin input (assumes Bash, Ksh, or Zsh):

      $ sed '$ s/.$//' <<< $'line one\nline two'
  line one
  line tw

To update the input file too (do not use if the input file is a symlink):

sed -i '$ s/.$//' somefile

Note:

  • On macOS, you’d have to use -i '' instead of just -i; for an overview of the pitfalls associated with -i, see the bottom half of this answer.
  • If you need to process very large input files and/or performance / disk usage are a concern and you’re using GNU utilities (Linux), see ImHere’s helpful answer.

More Related Contents:

  1. Better way to rename files based on multiple patterns
  2. Uppercasing First Letter of Words Using SED
  3. Bash script to remove ‘x’ amount of characters the end of multiple filenames in a directory?
  4. Looping through the content of a file in Bash
  5. Why should eval be avoided in Bash, and what should I use instead?
  6. How to permanently set $PATH on Linux/Unix [closed]
  7. Setting an argument with bash [duplicate]
  8. How to kill a child process after a given timeout in Bash?
  9. Environment variable substitution in sed
  10. How to generate a core dump in Linux on a segmentation fault?
  11. Aborting a shell script if any command returns a non-zero value
  12. Delete empty lines using sed
  13. How do I use sed to change my configuration files, with flexible keys and values?
  14. How to set environment variable for everyone under my linux system?
  15. Linux: copy and create destination dir if it does not exist
  16. What is the difference between using `sh` and `source`?
  17. Setting environment variables in Linux using Bash
  18. How to sort a file in-place?
  19. How do I syntax check a Bash script without running it?
  20. Is it OK to use the same input file as output of a piped command?
  21. When to wrap quotes around a shell variable?
  22. How do you normalize a file path in Bash?
  23. How do I get cURL to not show the progress bar?
  24. How do I remove newlines from a text file?
  25. Using grep and sed to find and replace a string
  26. Using `date` command to get previous, current and next month
  27. How to check if sed has changed a file
  28. Joining multiple fields in text files on Unix
  29. How do I delete all lines in a file starting from after a matching line?
  30. What are the rules for valid identifiers (e.g. functions, vars, etc) in Bash?

Leave a Comment