How to remove first/last character from a string using SED

How to remove first/last character from a string using SED
How to remove first/last character from a string using SED, Removing the last three characters from every filename, Removing first character from each filename/string, Removing last character from each filename/string

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How to remove first/last character from a string using SEDIn the context of having a list of files with .exe, .pdf, .jpg, .gif extensions and we need to remove these extensions, we need to use sed:

$ cat files
apache-1.3.39.exe
autoconf-wrapper-20070404.exe
glib-2.12.13.exe
libiconv-1.9.2_2.exe
mysql-client-5.0.45.exe
mysql-server-5.0.45_1.exe
p5-Storable-2.16.exe
pecl-APC-3.0.14.exe
php4-4.4.7_2.exe
php4-ctype-4.4.7_2.exe
php4-exif-4.4.7_2.exe
php4-extensions-1.0.exe
php4-ftp-4.4.7_2.exe
php4-gd-4.4.7_2.exe
php4-mysql-4.4.7_2.exe
php4-overload-4.4.7_2.exe
php4-pcre-4.4.7_2.exe

Removing the last three characters from every filename

$ cat files | sed 's/$.*$.../\1/'
apache-1.3.39.
autoconf-wrapper-20070404.
glib-2.12.13.
libiconv-1.9.2_2.
mysql-client-5.0.45.
mysql-server-5.0.45_1.
p5-Storable-2.16.
pecl-APC-3.0.14.
php4-4.4.7_2.
php4-ctype-4.4.7_2.
php4-exif-4.4.7_2.
php4-extensions-1.0.
php4-ftp-4.4.7_2.
php4-gd-4.4.7_2.
php4-mysql-4.4.7_2.
php4-overload-4.4.7_2.
php4-pcre-4.4.7_2.

(I used this example in order to make it more obvious).

Removing first character from each filename/string

$ cat files |sed 's/.$.*$/\1/'
pache-1.3.39.exe
utoconf-wrapper-20070404.exe
lib-2.12.13.exe
ibiconv-1.9.2_2.exe
ysql-client-5.0.45.exe
ysql-server-5.0.45_1.exe
5-Storable-2.16.exe
ecl-APC-3.0.14.exe
hp4-4.4.7_2.exe
hp4-ctype-4.4.7_2.exe
hp4-exif-4.4.7_2.exe
hp4-extensions-1.0.exe
hp4-ftp-4.4.7_2.exe
hp4-gd-4.4.7_2.exe
hp4-mysql-4.4.7_2.exe
hp4-overload-4.4.7_2.exe
hp4-pcre-4.4.7_2.exe

Using sed and regular expressions, we can replace characters in strings. In the last example I replaced any string in the form |one character followed by any other characters zero or more times| with the |any other characters 0 ore more times| .$.*$ in regular expressions terms matches any string that starts with any single character, followed by any other character 0-1-2-3... times (the brakets are being escaped by backslay ). Sed replaces this string with a new string that contains everything else after the first character in the previous string.

Removing last character from each filename/string

$ cat files |sed 's/$.*$./\1/'
apache-1.3.39.ex
autoconf-wrapper-20070404.ex
glib-2.12.13.ex
libiconv-1.9.2_2.ex
mysql-client-5.0.45.ex
mysql-server-5.0.45_1.ex
p5-Storable-2.16.ex
pecl-APC-3.0.14.ex
php4-4.4.7_2.ex
php4-ctype-4.4.7_2.ex
php4-exif-4.4.7_2.ex
php4-extensions-1.0.ex
php4-ftp-4.4.7_2.ex
php4-gd-4.4.7_2.ex
php4-mysql-4.4.7_2.ex
php4-overload-4.4.7_2.ex
php4-pcre-4.4.7_2.ex

Notice that in this last example the dot |one character| moved after |any other characters zero or more times|, resulting in the last character in the string (filename in this case).

This tutorial is not perfect but I hope it helps.

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Post comment:

1. Re: How to remove first/last character from a string using SED

Oracle Database Administrator by malik shahid at February 10th, 2010 - 15:06

It is very helpful. but can you please explain the regular expression working logic

2. Re: How to remove first/last character from a string using SED

gopher by JohnC at February 08th, 2010 - 11:44

Thanks very much .. saved a lot of time, not everybody is an expert in awk,sed etc!

3. Re: How to remove first/last character from a string using SED

Remove the character before the last character wi by Andrei at November 04th, 2009 - 16:50

Remove the character before the last character with SED http://forum.ivorde.ro/remove-the-character-before-the-last-character-with-sed-shell-scripting-t40.html

4. Re: How to remove first/last character from a string using SED

qus.. by srutho at November 04th, 2009 - 12:59

hw to delete the character before the last character in each line of a file????

5. Re: How to remove first/last character from a string using SED

sed by swap at September 14th, 2009 - 12:03

how to remove last but one character in a line using sed

6. Re: How to remove first/last character from a string using SED

Mr. by Tinku at September 13th, 2009 - 17:02

Question1:-How to remove/delete last but one character in everyline in a file using sed command.
question2:-How to remove first character in everyline in a file using sed command.
Questions3:-How to swap 3rd,4th words in a file using sed command

7. Re: How to remove first/last character from a string using SED

nice article by ujjwal b soni at December 24th, 2008 - 11:43

Hi,

Its really a nice article !!!

Cheers,

Ujjwal B Soni

baroda, gujarat, india

8. Re: How to remove first/last character from a string using SED

@sekhar by admin at November 04th, 2008 - 16:12

Check out this article: http://www.ivorde.ro/How_to_cut_out_first_last_n_characters_from_file_name-100.html It shows how to remove the first three lines from each file's name. It can easily be adapted to other tasks, if you need to.

9. Re: How to remove first/last character from a string using SED

how to apply the Command for Directory Files by sekhar at October 17th, 2008 - 13:45

hii dude,
of Course u'r scripts looks correct ,but i dont want to take input from the text files ,Instead of that my directory has so many files , and i need to cut the First three Characters from the Filenames.And the Operation should b Inplace(means the Next time i open the Directory it Should Contains the modified files ...

Thankq

10. Re: How to remove first/last character from a string using SED

cat "folder" ? by Nico at September 18th, 2008 - 21:40

I get a whole lot of "No such file or directory" if I try to do this in a folder.
I'm assuming you were doing this on a text file.
What if you wanted to batch rename a whole bunch of files, taking out the first n characters?

11. Re: How to remove first/last character from a string using SED

To Aerouge by Andrei at June 19th, 2008 - 17:33

You can use the above example also to remove first/last two/three and so on characters from a string. Just use dot(.) characters as more as the number of characters you want to remove or replace. URW

12. Re: How to remove first/last character from a string using SED

Great Tut... Kudos by Aerouge at June 17th, 2008 - 17:48

You have no idea how hard it is to find an article on this topic... and once I found your´s I could stop searching! Great work, percise, good examples and really helpfull!

Thanks a thousand times!