Mfcttrf

Are there any to-scale diagrams of the TRAPPIST-1 system?

Should I use the words "pyromancy" and "necromancy" even if they don't mean what people think they do?

Half filled water bottle

Is the internet in Madagascar faster than in UK?

Should an STL container avoid copying elements into themselves when the container is copied into itself?

How to force GCC to assume that a floating-point expression is non-negative?

Find feasible point in polynomial time in linear programming

Why does matter stay collapsed in the core, following a supernova explosion?

How do we improve collaboration with problematic tester team?

Why is there not a willingness from the world to step in between Pakistan and India?

Federal Pacific 200a main panel problem with oversized 100a 2pole breaker

Why not explainability is a metric for publishability?

Why does Windows store Wi-Fi passwords in a reversible format?

Talk interpreter

Shift lens vs move body?

How could a self contained organic body propel itself in space

Counting the triangles that can be formed from segments of given lengths

To what extent should we fear giving offense?

A first "Hangman" game in Python

What happens to transactions included in extinct or invalid blocks?

Is a Centaur PC considered an animal when calculating carrying capacity for vehicles?

Is a memoized pure function itself considered pure?

Did anybody find out it was Anakin who blew up the command center?

What is the function of modprobe in this code?

Grep contents before a colon

Why does adding a colon break this grep pattern?grep command giving errorExtend grep to find a match after the first matchHow to grep-inverse-match and exclude “before” and “after” linesgrep all the lines in a file and write line to a file from the pattern matching pointHow to include everything before Colon in Sed/Grep/…?Grep word within a file then copy the fileTo grep for a word before matching patternExtracting string via grep regex assertionsGrep/Awk for Value Between

.everyoneloves__top-leaderboard:empty,.everyoneloves__mid-leaderboard:empty,.everyoneloves__bot-mid-leaderboard:empty margin-bottom:0;

2

1

I have a text file on Linux where the contents are like below:

help.helloworld.com:latest.world.com
dev.helloworld.com:latest.world.com

I want to grep the contents before the colon like below:

help.helloworld.com
dev.helloworld.com

How can I do that within the terminal?

text-processing grep

share|improve this question

edited 8 hours ago

terdon♦

141k3434 gold badges290290 silver badges469469 bronze badges

asked 8 hours ago

Gabrial JohnasGabrial Johnas

11733 bronze badges

New contributor

Gabrial Johnas is a new contributor to this site. Take care in asking for clarification, commenting, and answering.
Check out our Code of Conduct.

• 
  
  
  

  
  

  
  
  
  
  
  

  
  
  The grep utility is used for looking for lines matching regular expressions. You could possibly use it here, but it would be more appropriate to use a tool that extracts data from fields given some delimiter, such as the cut utility.
  
  – Kusalananda♦
  7 hours ago
  
  

  
  
  
  

add a comment | 

2

1

I have a text file on Linux where the contents are like below:

help.helloworld.com:latest.world.com
dev.helloworld.com:latest.world.com

I want to grep the contents before the colon like below:

help.helloworld.com
dev.helloworld.com

How can I do that within the terminal?

text-processing grep

share|improve this question

edited 8 hours ago

terdon♦

141k3434 gold badges290290 silver badges469469 bronze badges

asked 8 hours ago

Gabrial JohnasGabrial Johnas

11733 bronze badges

New contributor

Gabrial Johnas is a new contributor to this site. Take care in asking for clarification, commenting, and answering.
Check out our Code of Conduct.

• 
  
  
  

  
  

  
  
  
  
  
  

  
  
  The grep utility is used for looking for lines matching regular expressions. You could possibly use it here, but it would be more appropriate to use a tool that extracts data from fields given some delimiter, such as the cut utility.
  
  – Kusalananda♦
  7 hours ago
  
  

  
  
  
  

add a comment | 

I have a text file on Linux where the contents are like below:

help.helloworld.com:latest.world.com
dev.helloworld.com:latest.world.com

I want to grep the contents before the colon like below:

help.helloworld.com
dev.helloworld.com

How can I do that within the terminal?

text-processing grep

share|improve this question

edited 8 hours ago

terdon♦

141k3434 gold badges290290 silver badges469469 bronze badges

asked 8 hours ago

Gabrial JohnasGabrial Johnas

11733 bronze badges

New contributor

Gabrial Johnas is a new contributor to this site. Take care in asking for clarification, commenting, and answering.
Check out our Code of Conduct.

help.helloworld.com:latest.world.com
dev.helloworld.com:latest.world.com

help.helloworld.com
dev.helloworld.com

share|improve this question

edited 8 hours ago

terdon♦

141k3434 gold badges290290 silver badges469469 bronze badges

asked 8 hours ago

Gabrial JohnasGabrial Johnas

11733 bronze badges

New contributor

Gabrial Johnas is a new contributor to this site. Take care in asking for clarification, commenting, and answering.
Check out our Code of Conduct.

share|improve this question

edited 8 hours ago

terdon♦

141k3434 gold badges290290 silver badges469469 bronze badges

asked 8 hours ago

Gabrial JohnasGabrial Johnas

11733 bronze badges

New contributor

Gabrial Johnas is a new contributor to this site. Take care in asking for clarification, commenting, and answering.
Check out our Code of Conduct.

edited 8 hours ago

terdon♦

141k3434 gold badges290290 silver badges469469 bronze badges

edited 8 hours ago

terdon♦

141k3434 gold badges290290 silver badges469469 bronze badges

asked 8 hours ago

Gabrial JohnasGabrial Johnas

11733 bronze badges

New contributor

Gabrial Johnas is a new contributor to this site. Take care in asking for clarification, commenting, and answering.
Check out our Code of Conduct.

asked 8 hours ago

Gabrial JohnasGabrial Johnas

11733 bronze badges

4 Answers
4

active

oldest

votes

1

Requires GNU grep. It would not work with the default grep on
e.g. macOS or any of the other BSDs.

Do you mean like this:

grep -oP '.*(?=:)' file

Output:

help.helloworld.com
dev.helloworld.com

share|improve this answer

edited 7 hours ago

answered 8 hours ago

guillermo chamorroguillermo chamorro

62311 silver badge1212 bronze badges

• 
  
  
  

  
  2
  

  
  
  
  
  
  

  
  
  If there are two or more colons on the line, this will print everything until the last one, so not what the OP needs. Try echo foo:bar:baz | grep -oP '.*(?=:)'. This will work for the OP's example, but not for the general case as described in the question.
  
  – terdon♦
  7 hours ago
  

  
  
  
  


• 
  
  
  

  
  

  
  
  
  
  
  

  
  
  there is only one colon and its working fine , but thanks for the update
  
  – Gabrial Johnas
  7 hours ago
  

  
  
  
  


• 
  
  
  

  
  2
  

  
  
  
  
  
  

  
  
  Also requires GNU grep. It would not work with the default grep on e.g. macOS or any of the other BSDs.
  
  – Kusalananda♦
  7 hours ago
  

  
  
  
  


• 
  
  
  

  
  

  
  
  
  
  
  

  
  
  @Kusalananda I edited the question adding your observation.
  
  – guillermo chamorro
  7 hours ago
  

  
  
  
  

add a comment | 

6

Or an alternative:

$ grep -o '^[^:]*' file
help.helloworld.com
dev.helloworld.com

This returns any characters beginning at the start of each line (^) which are no colons ([^:]*).

share|improve this answer

answered 8 hours ago

FreddyFreddy

6,94811 gold badge66 silver badges2424 bronze badges

add a comment | 

6

Would definitely recommend awk:

awk -F ':' 'print $1' file

Uses : as a field separator and prints the first field.

share|improve this answer

answered 7 hours ago

CentimaneCentimane

3,30311 gold badge1313 silver badges3636 bronze badges

add a comment | 

5

This is what cut is for:

$ cat file
help.helloworld.com:latest.world.com
dev.helloworld.com:latest.world.com
foo:baz:bar
foo

$ cut -d: -f1 file
help.helloworld.com
dev.helloworld.com
foo
foo

You just set the delimiter to : with -d: and tell it to only print the 1st field (-f1).

share|improve this answer

answered 7 hours ago

terdon♦terdon

141k3434 gold badges290290 silver badges469469 bronze badges

add a comment | 

Your Answer

StackExchange.ready(function()
var channelOptions =
tags: "".split(" "),
id: "106"
;
initTagRenderer("".split(" "), "".split(" "), channelOptions);

StackExchange.using("externalEditor", function()
// Have to fire editor after snippets, if snippets enabled
if (StackExchange.settings.snippets.snippetsEnabled)
StackExchange.using("snippets", function()
createEditor();
);

else
createEditor();

);

function createEditor()
StackExchange.prepareEditor(
heartbeatType: 'answer',
autoActivateHeartbeat: false,
convertImagesToLinks: false,
noModals: true,
showLowRepImageUploadWarning: true,
reputationToPostImages: null,
bindNavPrevention: true,
postfix: "",
imageUploader:
brandingHtml: "Powered by u003ca class="icon-imgur-white" href="https://imgur.com/"u003eu003c/au003e",
contentPolicyHtml: "User contributions licensed under u003ca href="https://creativecommons.org/licenses/by-sa/3.0/"u003ecc by-sa 3.0 with attribution requiredu003c/au003e u003ca href="https://stackoverflow.com/legal/content-policy"u003e(content policy)u003c/au003e",
allowUrls: true
,
onDemand: true,
discardSelector: ".discard-answer"
,immediatelyShowMarkdownHelp:true
);



);

Gabrial Johnas is a new contributor. Be nice, and check out our Code of Conduct.

draft saved

draft discarded

Sign up or log in

StackExchange.ready(function ()
StackExchange.helpers.onClickDraftSave('#login-link');
);

Sign up using Google

Sign up using Facebook

Sign up using Email and Password

Post as a guest

Name

Email

Required, but never shown

StackExchange.ready(
function ()
StackExchange.openid.initPostLogin('.new-post-login', 'https%3a%2f%2funix.stackexchange.com%2fquestions%2f537707%2fgrep-contents-before-a-colon%23new-answer', 'question_page');

);

Post as a guest

Name

Email

Required, but never shown

1

Requires GNU grep. It would not work with the default grep on
e.g. macOS or any of the other BSDs.

Do you mean like this:

grep -oP '.*(?=:)' file

Output:

help.helloworld.com
dev.helloworld.com

share|improve this answer

edited 7 hours ago

answered 8 hours ago

guillermo chamorroguillermo chamorro

62311 silver badge1212 bronze badges

• 
  
  
  

  
  2
  

  
  
  
  
  
  

  
  
  If there are two or more colons on the line, this will print everything until the last one, so not what the OP needs. Try echo foo:bar:baz | grep -oP '.*(?=:)'. This will work for the OP's example, but not for the general case as described in the question.
  
  – terdon♦
  7 hours ago
  

  
  
  
  


• 
  
  
  

  
  

  
  
  
  
  
  

  
  
  there is only one colon and its working fine , but thanks for the update
  
  – Gabrial Johnas
  7 hours ago
  

  
  
  
  


• 
  
  
  

  
  2
  

  
  
  
  
  
  

  
  
  Also requires GNU grep. It would not work with the default grep on e.g. macOS or any of the other BSDs.
  
  – Kusalananda♦
  7 hours ago
  

  
  
  
  


• 
  
  
  

  
  

  
  
  
  
  
  

  
  
  @Kusalananda I edited the question adding your observation.
  
  – guillermo chamorro
  7 hours ago
  

  
  
  
  

add a comment | 

1

Requires GNU grep. It would not work with the default grep on
e.g. macOS or any of the other BSDs.

Do you mean like this:

grep -oP '.*(?=:)' file

Output:

help.helloworld.com
dev.helloworld.com

share|improve this answer

edited 7 hours ago

answered 8 hours ago

guillermo chamorroguillermo chamorro

62311 silver badge1212 bronze badges

• 
  
  
  

  
  2
  

  
  
  
  
  
  

  
  
  If there are two or more colons on the line, this will print everything until the last one, so not what the OP needs. Try echo foo:bar:baz | grep -oP '.*(?=:)'. This will work for the OP's example, but not for the general case as described in the question.
  
  – terdon♦
  7 hours ago
  

  
  
  
  


• 
  
  
  

  
  

  
  
  
  
  
  

  
  
  there is only one colon and its working fine , but thanks for the update
  
  – Gabrial Johnas
  7 hours ago
  

  
  
  
  


• 
  
  
  

  
  2
  

  
  
  
  
  
  

  
  
  Also requires GNU grep. It would not work with the default grep on e.g. macOS or any of the other BSDs.
  
  – Kusalananda♦
  7 hours ago
  

  
  
  
  


• 
  
  
  

  
  

  
  
  
  
  
  

  
  
  @Kusalananda I edited the question adding your observation.
  
  – guillermo chamorro
  7 hours ago
  

  
  
  
  

add a comment | 

Requires GNU grep. It would not work with the default grep on
e.g. macOS or any of the other BSDs.

Do you mean like this:

grep -oP '.*(?=:)' file

Output:

help.helloworld.com
dev.helloworld.com

share|improve this answer

edited 7 hours ago

answered 8 hours ago

guillermo chamorroguillermo chamorro

62311 silver badge1212 bronze badges

grep -oP '.*(?=:)' file

help.helloworld.com
dev.helloworld.com

share|improve this answer

edited 7 hours ago

answered 8 hours ago

guillermo chamorroguillermo chamorro

62311 silver badge1212 bronze badges

answered 8 hours ago

guillermo chamorroguillermo chamorro

62311 silver badge1212 bronze badges

answered 8 hours ago

guillermo chamorroguillermo chamorro

62311 silver badge1212 bronze badges

6

Or an alternative:

$ grep -o '^[^:]*' file
help.helloworld.com
dev.helloworld.com

This returns any characters beginning at the start of each line (^) which are no colons ([^:]*).

share|improve this answer

answered 8 hours ago

FreddyFreddy

6,94811 gold badge66 silver badges2424 bronze badges

add a comment | 

6

Or an alternative:

$ grep -o '^[^:]*' file
help.helloworld.com
dev.helloworld.com

This returns any characters beginning at the start of each line (^) which are no colons ([^:]*).

share|improve this answer

answered 8 hours ago

FreddyFreddy

6,94811 gold badge66 silver badges2424 bronze badges

add a comment | 

Or an alternative:

$ grep -o '^[^:]*' file
help.helloworld.com
dev.helloworld.com

This returns any characters beginning at the start of each line (^) which are no colons ([^:]*).

share|improve this answer

answered 8 hours ago

FreddyFreddy

6,94811 gold badge66 silver badges2424 bronze badges

$ grep -o '^[^:]*' file
help.helloworld.com
dev.helloworld.com

share|improve this answer

answered 8 hours ago

FreddyFreddy

6,94811 gold badge66 silver badges2424 bronze badges

answered 8 hours ago

FreddyFreddy

6,94811 gold badge66 silver badges2424 bronze badges

answered 8 hours ago

FreddyFreddy

6,94811 gold badge66 silver badges2424 bronze badges

6

Would definitely recommend awk:

awk -F ':' 'print $1' file

Uses : as a field separator and prints the first field.

share|improve this answer

answered 7 hours ago

CentimaneCentimane

3,30311 gold badge1313 silver badges3636 bronze badges

add a comment | 

6

Would definitely recommend awk:

awk -F ':' 'print $1' file

Uses : as a field separator and prints the first field.

share|improve this answer

answered 7 hours ago

CentimaneCentimane

3,30311 gold badge1313 silver badges3636 bronze badges

add a comment | 

Would definitely recommend awk:

awk -F ':' 'print $1' file

Uses : as a field separator and prints the first field.

share|improve this answer

answered 7 hours ago

CentimaneCentimane

3,30311 gold badge1313 silver badges3636 bronze badges

awk -F ':' 'print $1' file

share|improve this answer

answered 7 hours ago

CentimaneCentimane

3,30311 gold badge1313 silver badges3636 bronze badges

answered 7 hours ago

CentimaneCentimane

3,30311 gold badge1313 silver badges3636 bronze badges

answered 7 hours ago

CentimaneCentimane

3,30311 gold badge1313 silver badges3636 bronze badges

5

This is what cut is for:

$ cat file
help.helloworld.com:latest.world.com
dev.helloworld.com:latest.world.com
foo:baz:bar
foo

$ cut -d: -f1 file
help.helloworld.com
dev.helloworld.com
foo
foo

You just set the delimiter to : with -d: and tell it to only print the 1st field (-f1).

share|improve this answer

answered 7 hours ago

terdon♦terdon

141k3434 gold badges290290 silver badges469469 bronze badges

add a comment | 

5

This is what cut is for:

$ cat file
help.helloworld.com:latest.world.com
dev.helloworld.com:latest.world.com
foo:baz:bar
foo

$ cut -d: -f1 file
help.helloworld.com
dev.helloworld.com
foo
foo

You just set the delimiter to : with -d: and tell it to only print the 1st field (-f1).

share|improve this answer

answered 7 hours ago

terdon♦terdon

141k3434 gold badges290290 silver badges469469 bronze badges

add a comment | 

This is what cut is for:

$ cat file
help.helloworld.com:latest.world.com
dev.helloworld.com:latest.world.com
foo:baz:bar
foo

$ cut -d: -f1 file
help.helloworld.com
dev.helloworld.com
foo
foo

You just set the delimiter to : with -d: and tell it to only print the 1st field (-f1).

share|improve this answer

answered 7 hours ago

terdon♦terdon

141k3434 gold badges290290 silver badges469469 bronze badges

$ cat file
help.helloworld.com:latest.world.com
dev.helloworld.com:latest.world.com
foo:baz:bar
foo

$ cut -d: -f1 file
help.helloworld.com
dev.helloworld.com
foo
foo

share|improve this answer

answered 7 hours ago

terdon♦terdon

141k3434 gold badges290290 silver badges469469 bronze badges

answered 7 hours ago

terdon♦terdon

141k3434 gold badges290290 silver badges469469 bronze badges

answered 7 hours ago

terdon♦terdon

141k3434 gold badges290290 silver badges469469 bronze badges