Let us consider a file with the sample contents as below:
$ cat file Cygwin Unix Linux Solaris AIX1. Delete the 1st line or the header line:
$ sed '1d' file Unix Linux Solaris AIXd command is to delete a line. 1d means to delete the first line.
The above command will show the file content by deleting the first line. However, the source file remains unchanged. To update the original file itself with this deletion or to make the changes permanently in the source file, use the -i option. The same is applicable for all the other examples.
sed -i '1d' fileNote: -i option in sed is available only if it is GNU sed. If not GNU, re-direct the sed output to a file, and rename the output file to the original file.
2. Delete a particular line, 3rd line in this case:
$ sed '3d' file Cygwin Unix Solaris AIX3. Delete the last line or the trailer line of the file:
$ sed '$d' file Cygwin Unix Linux Solaris$ indicates the last line.
4. Delete a range of lines, from 2nd line till 4th line:
$ sed '2,4d' file Cygwin AIXThe range is specified using the comma operator.
5. Delete lines other than the specified range, line other than 2nd till 4th here:
$ sed '2,4!d' file Unix Linux SolarisThe ! operator indicates negative condition.
6. Delete the first line AND the last line of a file, i.e, the header and trailer line of a file.
$ sed '1d;$d' file Unix Linux SolarisMultiple conditions are separated using the ';' operator. Similarly, say to delete 2nd and 4th line, you can use: '2d;3d'.
7. Delete all lines beginning with a particular character, 'L' in this case:
$ sed '/^L/d' file Cygwin Unix Solaris AIX'^L' indicates lines beginning with L.
8. Delete all lines ending with a particular character, 'x' in this case:
$ sed '/x$/d' file Cygwin Solaris AIX'x$' indicates lines ending with 'x'. AIX did not get deleted because the X is capital.
9. Delete all lines ending with either x or X, i.e case-insensitive delete:
$ sed '/[xX]$/d' file Cygwin Solaris[xX] indicates either 'x' or 'X'. So, this will delete all lines ending with either small 'x' or capital 'X'.
10. Delete all blank lines in the file
$ sed '/^$/d' file Cygwin Unix Linux Solaris AIX'^$' indicates lines containing nothing and hence the empty lines get deleted. However, this wont delete lines containing only some blank spaces.
11. Delete all lines which are empty or which contains just some blank spaces:
$ sed '/^ *$/d' file Cygwin Unix Linux Solaris AIX'*' indicates 0 or more occurrences of the previous character. '^ *$' indicates a line containing zero or more spaces. Hence, this will delete all lines which are either empty or lines with only some blank spaces.
12. Delete all lines which are entirely in capital letters:
$ sed '/^[A-Z]*$/d' file Cygwin Unix Linux Solaris[A-Z] indicates any character matching the alphabets in capital.
13. Delete the lines containing the pattern 'Unix'.
$ sed '/Unix/d' file Cygwin Linux Solaris AIXThe pattern is specified within a pair of slashes.
14. Delete the lines NOT containing the pattern 'Unix':
$ sed '/Unix/!d' file Unix15. Delete the lines containing the pattern 'Unix' OR 'Linux':
$ sed '/Unix\|Linux/d' file Cygwin Solaris AIXThe OR condition is specified using the | operator. In order not to get the pipe(|) interpreted as a literal, it is escaped using a backslash.
16. Delete the lines starting from the 1st line till encountering the pattern 'Linux':
$ sed '1,/Linux/d' file Solaris AIXEarlier, we saw how to delete a range of lines. Range can be in many combinations: Line ranges, pattern ranges, line and pattern, pattern and line.
17. Delete the lines starting from the pattern 'Linux' till the last line:
$ sed '/Linux/,$d' file Cygwin Unix18. Delete the last line ONLY if it contains the pattern 'AIX':
$ sed '${/AIX/d;}' file Cygwin Unix Linux Solaris$ is for the last line. To delete a particular line only if it contains the pattern AIX, put the line number in place of the $. This is how we can implement the 'if' condition in sed.
19. Delete the last line ONLY if it contains either the pattern 'AIX' or 'HPUX':
$ sed '${/AIX\|HPUX/d;}' file Cygwin Unix Linux Solaris20. Delete the lines containing the pattern 'Solaris' only if it is present in the lines from 1 to 4.
$ sed '1,4{/Solaris/d;}' file Cygwin Unix Linux AIXThis will only delete the lines containing the pattern Solaris only if it is in the 1st four lines, nowhere else.
21. Delete the line containing the pattern 'Unix' and also the next line:
$ sed '/Unix/{N;d;}' file Cygwin Solaris AIXN command reads the next line in the pattern space. d deletes the entire pattern space which contains the current and the next line.
22. Delete only the next line containing the pattern 'Unix', not the very line:
$ sed '/Unix/{N;s/\n.*//;}' file Cygwin Unix Solaris AIXUsing the substitution command s, we delete from the newline character till the end, which effective deletes the next line after the line containing the pattern Unix.
23. Delete the line containing the pattern 'Linux', also the line before the pattern:
$ sed -n '/Linux/{s/.*//;x;d;};x;p;${x;p;}' file | sed '/^$/d' Cygwin Solaris AIX
A little tricky ones. In order to delete the line prior to the pattern,we store every line in a buffer called as hold space. Whenever the pattern matches, we delete the content present in both, the pattern space which contains the current line, the hold space which contains the previous line.
Let me explain this command: 'x;p;' ; This gets executed for every line. x exchanges the content of pattern space with hold space. p prints the pattern space. As a result, every time, the current line goes to hold space, and the previous line comes to pattern space and gets printed. When the pattern /Linux/ matches, we empty(s/.*//) the pattern space, and exchange(x) with the hold space(as a result of which the hold space becomes empty) and delete(d) the pattern space which contains the previous line. And hence, the current and the previous line gets deleted on encountering the pattern Linux. The ${x;p;} is to print the last line which will remain in the hold space if left.
The second part of sed is to remove the empty lines created by the first sed command.
24. Delete only the line prior to the line containing the pattern 'Linux', not the very line:
$ sed -n '/Linux/{x;d;};1h;1!{x;p;};${x;p;}' file Cygwin Linux Solaris AIX
This is almost same as the last one with few changes. On encountering the pattern /Linux/, we exchange(x) and delete(d). As a result of exchange, the current line remains in hold space, and the previous line which came into pattern space got deleted.
1h;1!{x;p;} - 1h is to move the current line to hold space only if it first line. Exchange and print for all the other lines. This could easily have been simply: x;p . The drawback is it gives an empty line at the beginning because during the first exchange between the pattern space and hold space, a new line comes to pattern space since hold space is empty.
25. Delete the line containing the pattern 'Linux', the line before, the line after:
$ sed -n '/Linux/{N;s/.*//;x;d;};x;p;${x;p;}' file | sed '/^$/d' Cygwin AIXWith the explanations of the last 2 commands, this should be fairly simple to understand.
Nice collection of commands !! Keep posting such Good articles !! :)
ReplyDeleteThank you for this great article. I will use as a reference! I have a question about number 24. How to delete line before Linux only if it is empty or has only white spaces? Thank you again!
ReplyDeleteThis should do James:
Delete$ sed -n '/Linux/{x;/^ *$/d;x;};1h;1!{x;p;};${x;p;}' file
Thank you Guru! You are very good! I am new to Shell scripting, only been at it for a few months. I bookmarked this article for future reference.
ReplyDeleteExcellent article!
ReplyDeleteHow can I do to delete all lines between 2 parameters?
i.e.: I want to remove all lines between 'Linux' and 'AIX' from the file called 'test' and I don't know how many lines are between tehy, so I need to use two parameters.
Thank you in advance
almost same as in example 17..just replace $ with /AIX/
Deletegreat article with examples Guru, appreciate it.
ReplyDeleteThanks Anies
DeleteNice article......... can u please post commond for
ReplyDeletehow to get top 10 records and last 10 records of a file.
Use the head(to get top 10) and tail(to get last 10) commands for this.
DeleteGood examples.Can you tell me to delete a record if set of columns are null/blank.Say total 10 columns in which 2,5,7,8 columns are coming as null/blank for some records.Those should be removed from the file.I am using awk command but how will be the performance if millions of records are there in a file.
ReplyDeleteSomething like this(not tested):
Deleteawk '{if ($2 =="" && $5 == "")next}1' file
It might take a few seconds to execute it, but its ok. Whenever a file is big, just make sure every command you use for per record processing should be justified to be there.
For any technical questions, please post the question in our forum: forum.theunixschool.com
Hi, Very nice read... however, I was not able to delete a line from a csv file which contained the pattern ',Pub,Totals:, and so, on,' So i used the below command.
ReplyDeletesed '/^,Pub,Totals:/d' $filename... any help is greatly appreciated.
Thanks
Dhruuv
The command you used is correct one. However, only if your file content is beginning with ',Pub,...', use the ^, else drop it.
DeleteHi,
ReplyDeletevery good example and easy to understand. But i have a question. How to delete lines and matched patterns between 2 patterns without deleting the second pattern? i used this:
sed '/pattern1/,/pattern/{//p;d;}' inputfile
It deleted everything between the patterns but remain the matched patterns. I want to delete pattern1 too. appreciate your help on this.
Thanks.
sed '/pattern1/,/pattern/{/pattern1/d;p;}' inputfile
DeleteIt is do helpful! I wonder if there is a way to delete more than 1 line before a pattern?
ReplyDeletehi,
ReplyDeletehow to delete last 10 lines from a file.
thanks,
x=$(wc -l <file)
Deletex=$(expr $x - 10)
sed -n "1,$x p" file
Hi Guru, great article. I know this might be really straightforward, but I don't seem to get the right syntax. I want to delete the line below a pattern (not the pattern) only if it is blank (you answered this for the line above, but I can't make it work for my case). Thank you.
ReplyDeleteTo delete a line after the pattern if it is blank:
Deletesed '/Unix/{n;/^$/d;}' file
Hi
ReplyDeleteHow I delele only second and fourth matching line , and replace only second an fourth matching line.
Thank you
Hi
ReplyDeletehow do i Delete only the 3rd next line containing the pattern 'Unix', not the very line.
Suppose i have a file-->
tr
Ansh
Anshuman
Raj
L
M
M
N
So i want to remove only the third line after tr.
sed '/tr/{n;n;n;d;}' file
DeleteVery good collection of sed commands!
ReplyDeleteHi Guru, Nice Article!
ReplyDeleteTwo doubts:-
I have one XML having multiple header segments. I need to delete multiple segments(Part of header) from a large XML file(around 150 MB):
The header segment consist of following segments:
Transaction-834
Internal-Properties
Segment-ST
Segment-BGN
I used the following command:
sed -e '/Transaction-834/d;/Internal-Properties/d;/Segment-ST/d;/Segment-BGN/d' Input_File > New_File
With this command I am able to delete these multiple segments for a small XML file, but when I am trying to delete from this huge file (150 MB size) I am getting following error: "input line too long".
Any idea how to read and delete the segments from this huge XML file using sed or any other command?
Also is there any limit upto which sed command is able to read the file and perform action?
Thanks in advance!
Older sed has these problems. Use GNU sed. Try inserting a new line character after the long line and try once.
DeleteHi Guru,
ReplyDeleteThis was so helpful. I have a quick question.
I need to match a string and delete the previous lines (not the matched line) from a CSV file. My file would look like:
6,ZYX 0006/11262013,SLK,SLK,ABN,10:00:45.302765,19:00:00.000000,19:00:00.000000,19:00:00.000000,0,0,0,0,0,0,0,0,0,0,0,0,N
7,ZYX 0007/11262013,SLK,SLK,ADI,10:00:45.302774,19:00:00.000000,19:00:00.000000,19:00:00.000000,0,0,0,0,0,0,0,0,0,0,0,0,N
8,ZYX 0008/11262013,SLK,SLK,ADI,10:00:45.302780,19:00:00.000000,19:00:00.000000,19:00:00.000000,0,0,0,0,0,0,0,0,0,0,0,0,N
920,ABY 4531/11262013,#DM02,SLK,KEY,10:28:36.221893,10:28:36.234889,19:00:00.000000,19:00:00.000000,0,0,0,0,0,0,0,0,0,0,0,0,N
921,AAA 0110/11262013,#DM02,SLK,MDZ,10:28:36.233397,10:28:36.311391,19:00:00.000000,19:00:00.000000,0,0,0,0,0,0,0,0,0,0,0,0,N
Looks like it is example 24.
DeleteHi guru, i want to delete after and before character and get the number in between.
ReplyDelete2h31m45s
5h05m44s
want to get only number 31 or 05 between h and m
$ echo 2h31m45s | sed -r 's/.*h([^m]+)m.*/\1/'
Delete31
These are great! Is there a way to delete a pattern itself (without deleting the line it occurs on) in a file? I have a csv file that has filenames in the third column. I need to strip off the extension ONLY, and keep everything else. (e.g. remove .flv) from each line that has it in the column. Thanks!
ReplyDeleteTo just delete a pattern, check this link:
Deletehttp://www.theunixschool.com/2014/08/sed-examples-remove-delete-chars-from-line-file.html
hi Guru,
ReplyDeleteI am trying to get the contents between two instances of a word.
Basically I want to delete all lines before the 3rd instance of the word "cheese" and I want to remove all lines (including the containing one) of the 4th instance of the word cheese. So I am left with what is in between only.
Is this possible using just sed?
Please post this in Q&A(tab before contact). Also give an example input file and output expected.
DeleteHello,
ReplyDeleteHow to delete line number 3,6,9,12,15,18,21,24 and so on? The pattern is line number +3.
Thanks
To delete every 3rd line :
Deletesed 'n;n;d' file
Hi,
ReplyDeleteHow do I delete all entries in a file A from another file B that contains some IDs?
For instance, file A has data like
A1 1 2 3
A2 2 3 4
A3 3 4 5
And file B has entries like
A1
A2
How do I delete all lines from file A whereever ids match to file B?
awk would be better suited for this, not sed.
DeleteI Want to delete the record if I find a word in the fixed length(5-7). How can I do this?
ReplyDeleteawk is better for this. To get lines whose length is not 5:
Delete$ awk 'length($0)!=5' file
How to delete a line till the time pattern is matched. This line contains pattern more than twice.
ReplyDeletee.g.
The main class is going to start after class 4.
Result should be : "class is going to start after class 4."
I am using sed command : sed -e 's/.*\(class.*\)/\1/'
This is giving incorrect result "class 4"
Can you please share how can i get the desired result using sed.
$ x="The main class is going to start after class 4"
Delete$ echo $x | sed 's/[^c]*\(class.*\)/\1/'
class is going to start after class 4
$
Hi Guru,
ReplyDeleteI need delete the line containing the pattern 'Linux', the 2 lines before and the line after
Before:
AIX
HP
Linux
Solaris
Tru64
After command:
Tru64
Can you help me?
Thanks
Nice artical Guru
ReplyDeleteHi Guru,
ReplyDeleteI have the following text in one file
pattern1
line1
line2
pattern2
line3
line4
line5
pattern1
line6
line7
pattern2
line8
line9
pattern1
line10
pattern2
I want to replace the first occurrence of the block between pattern1 and pattern2 with some-text and delete the remaining 2 occurrences of the matching block. So the output should look like this:
some-text
line3
line4
line5
line8
line9
Help please. Thanks!
I have a csv file which contains 65000 lines (Size approximately 28 mb). In each of the lines certain path in the beginning is given e.g. "c:\abc\bcd\def\123\456". Now let say the path "c:\abc\bcd\" is common in all the lines and rest of the content is different. What i have to do is to remove the common part (In this case "c:\abc\bcd\") from all the lines.
ReplyDeleteCan any of you please help me out with this ? Also apologies in advance if i have mistakenly not followed any of the forum rules to ask this question.
Anurag,
ReplyDeleteA simple sed command like the following can accomplish this. First I created a short sample file with two matches and also one similar path starting with "d" instead of "c".
$ more inputfile
This is a sample file with heading
c:\abc\bcd\rest\of\path
c:\abc\bcd\more
d:\abc\bcd\more
d:\abc\def\ghi
My sed command:
sed 's&c:\\abc\\bcd\\&&' inputfile > outputfile
The resulting output is:
$ more outputfile
This is a sample file with heading
rest\of\path
more
d:\abc\bcd\more
d:\abc\def\ghi
- The "&" is used as a sed delimiter to make it more readable, since your pattern includes backslashes.
- The double backslashes "\\" are necessary since \ is used to escape special characters.
Hope this helps!
R
Thanks for the help. I'll try this and get back.
DeleteThis is gold information . Thank you for sharing it with us.
ReplyDeleteTotally agree with Ivan's comment above.Thank you very much Guru.
ReplyDeleteI have a.txt as follows and I am looking for b.txt
Header
Page: 1
column1 column2
- - - - - - - -
data11 data21
data12 data22
data13 data23
data14 data24
Header
Page: 2
column1 column2
- - - - - - - -
data15 data25
data16 data26
data17 data27
data18 data28
Header
Page: 3
column1 column2
- - - - - - - -
data19 data29
data20 data30
Expected output b.txt
Header
Page: 1
column1 column2
- - - - - - - -
data11 data21
data12 data22
data13 data23
data14 data24
data15 data25
data16 data26
data17 data27
data18 data28
data19 data29
data20 data30
I tried with sed '/Header/,/---/'d a.txt >b.txt
but in that process I am losing first occurance of header as well.
I wish to start above command from line 5, however I could not build one.
Tried sed '5,/Header/,/---/'d a.txt >b.txt, but its seems wrong syntax.
any inputs, help?
To get from 5th line, you can do like this:
Deletesed '5,${/Header/,/- - -/d;}' a.txt
Alternatively, if the content of a.txt is something you got out of a sql query, by adding the "set pagesize 0", automatically you will get the header only once..
Hi Guruprasad,
DeleteI have another issue referencing same example above, only change is every input file has Trailer info at the end appearing only once (showing the filtering/selection criteria).
I wish to retain first header, deleting all in headers appearing on subsequent pages. The solution provided by you perfectly works in that case. however in the process trailer (end of report) information appearing at the end also gets removed. Do we have any way to retain it .
Thank you very much.
Hi Guru,
ReplyDeleteHelp me out in this please.
i have text file abc.txt
L1137Q1 shantanu 040013.15 L Prashant .00
L134AQ1 Prashant .00 L shantanu 040013.15
L1337Q1 shantanu 040013.15 L Prashant .00
i need to delete line containing pattern " Prashant" in 2nd coloumn only,
output must be
L1137Q1 shantanu 040013.15 L Prashant .00
L1337Q1 shantanu 040013.15 L Prashant .00
Thank you in advance.
This is a typical candidate for awk:
Deleteawk '$2 !="Prashant"' file
what is the command to find a word in a line, then deleting (that line and previous line)
ReplyDeleteexample, I want to search for the word JDK, delete the JDK line and the previous line.
INPUT
-------------------------
Version 5.1
Version 5.1.1.12
ID BASE
Version 1.4.2
ID JDK
Version 5.1
Version 1.4.2
ID JDK
Version 5.1.1.12
ID ND
OUTPUT
---------------------------
Version 5.1
Version 5.1.1.12
ID BASE
Version 5.1
Version 5.1.1.12
ID ND
Refer to example 23
DeleteHow do you "sed" out multiple particular lines?
ReplyDeleteSay I want to sed line # 10,11,16,17,38,37 and 40?
sed -n '10p;11p;16p;17p;' file
DeleteI'm facing a issue in deleting a line having 'NUL' special character.
ReplyDeleteI used the below command
sed '/^@/d' test.csv
but this is removing only the 'NUL' character and not the line it contains. Can someone help on this.
23. doesn't work in ksh on AIX :( man! I really need it!
ReplyDeleteOne of the best article which explains useful sed command with examples
ReplyDeleteThanks for the examples. Could you show us how to, as a variation of 25?
ReplyDeleteDelete the line containing the pattern 'Linux', the line before, 2 lines after.
Hi, how do i delete the last n lines? i mean.. i have
ReplyDelete1111
2222
3333
4444
5555
and i want to remove from 3 till the end and get this
1111
2222
Thanks in advance
$ y=$(wc -l<file)
Delete$ let x=y-3+1
$ sed "$x,$y d" file
Hi, how do I delete everything between two patterns, including the patterns. The start and end of pattern could be on different lines.
ReplyDeleteE.g. if input is
start aaa end bbb ccc
aaa start bb end cc
aa bb cc
dd start ee
ff end gg
The output should be
bbb ccc
aaa cc
aa bb cc
dd
gg
Thanks!
That was really awesome stuff I learnt today!!!! Thanks for the detailed explanation
ReplyDeleteHello, ur tutorial is really being helpfull for beginners.........
ReplyDeletein my case i need to check every 17th col of the lines (row)in a file and if a particular character is found (say B) i need to delete the whole line...... please help
Hello.
ReplyDeleteHow can i delete lines where all the points in the line are same
line 1: 40 50 60 70 80
line 2: 30 50 50 90 100
line 3: 50 50 50 50 50
line 4: 20 15 20 32 45
How can i delete only lines like line 3 where all the points are 50. Line 1 and 2 also has 50 but not for all the points.
Thanks