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Aliased pipeline using head and cut

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3

I'd like to create an alias to have a quick view of the table format files with comma separator:

alias thead='head | cut -d, -f1- | column -s, -t'

Later using it like this

thead file.csv

However, it doesn't work. What would be the correct syntax?

bash alias

share|improve this question

edited 44 mins ago

Kusalananda

131k17250409

asked 1 hour ago

Max LiMax Li

1184

New contributor

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

• 
  
  
  

  
  1
  

  
  
  
  
  
  

  
  
  something is missing after the "-d"
  
  – Rui F Ribeiro
  1 hour ago
  

  
  
  
  


• 
  
  
  

  
  

  
  
  
  
  
  

  
  
  @RuiFRibeiro yep, a typo, thx
  
  – Max Li
  1 hour ago
  

  
  
  
  

add a comment | 

3

I'd like to create an alias to have a quick view of the table format files with comma separator:

alias thead='head | cut -d, -f1- | column -s, -t'

Later using it like this

thead file.csv

However, it doesn't work. What would be the correct syntax?

bash alias

share|improve this question

edited 44 mins ago

Kusalananda

131k17250409

asked 1 hour ago

Max LiMax Li

1184

New contributor

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

• 
  
  
  

  
  1
  

  
  
  
  
  
  

  
  
  something is missing after the "-d"
  
  – Rui F Ribeiro
  1 hour ago
  

  
  
  
  


• 
  
  
  

  
  

  
  
  
  
  
  

  
  
  @RuiFRibeiro yep, a typo, thx
  
  – Max Li
  1 hour ago
  

  
  
  
  

add a comment | 

I'd like to create an alias to have a quick view of the table format files with comma separator:

alias thead='head | cut -d, -f1- | column -s, -t'

Later using it like this

thead file.csv

However, it doesn't work. What would be the correct syntax?

bash alias

share|improve this question

edited 44 mins ago

Kusalananda

131k17250409

asked 1 hour ago

Max LiMax Li

1184

New contributor

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

alias thead='head | cut -d, -f1- | column -s, -t'

thead file.csv

share|improve this question

edited 44 mins ago

Kusalananda

131k17250409

asked 1 hour ago

Max LiMax Li

1184

New contributor

Max Li 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 44 mins ago

Kusalananda

131k17250409

asked 1 hour ago

Max LiMax Li

1184

New contributor

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

edited 44 mins ago

Kusalananda

131k17250409

edited 44 mins ago

Kusalananda

131k17250409

asked 1 hour ago

Max LiMax Li

1184

New contributor

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

asked 1 hour ago

Max LiMax Li

1184

2 Answers
2

active

oldest

votes

4

For anything more advanced than a simple command, use a shell function instead of an alias:

thead () {

    head "$1" | cut -d, -f1- | column -s, -t

}

This shell function would run head on its first argument, and then send the result through the pipeline.

Or,

thead () {

    head "$2" | cut -d "$1" -f1- | column -s, -t

}

... to be able to use it as

thead ',' filename

Or even, to allow for an optional delimiter (and use comma if none is given),

thead () {

    local delim=','



    if [ "$#" -gt 1 ]; then

        delim=$1

        shift

    fi



    head "$1" | cut -d "$delim" -f1- | column -s, -t

}

The function definition above could be placed wherever you usually define aliases.

---

The issue with having a pipeline in an alias is that when you use the alias with an argument, this argument would be added to the end of the pipeline, not after the first command in the pipeline.

---

The bash manual contains the sentence

For almost every purpose, aliases are superseded by shell functions.

share|improve this answer

edited 23 mins ago

answered 1 hour ago

KusalanandaKusalananda

131k17250409

• 
  
  
  

  
  

  
  
  
  
  
  

  
  
  that's good, do you know btw how can I adjust it to accept a separator as a parameter to thead?
  
  – Max Li
  1 hour ago
  

  
  
  
  


• 
  
  
  

  
  

  
  
  
  
  
  

  
  
  @MaxLi See updated answer.
  
  – Kusalananda
  1 hour ago
  

  
  
  
  

add a comment | 

2

alias expansion is just text substitution which is parsed again by the shell, so when you do:

thead file.csv

That's just replaced with:

head | cut -d, -f1- | column -s, -t file.csv

and interpreted again.

If you had written:

<file.csv thead

or

cat file.csv | thead

or

{ thead; } < file.csv

It would have worked as it would have been replaced with:

<file.csv head | cut -d, -f1- | column -s, -t

cat file.csv | head | cut -d, -f1- | column -s, -t

{ head | cut -d, -f1- | column -s, -t; } < file.csv

respectively. In any case, as @Kusalananda says, it's much better to use functions or scripts than aliases for that. Here, I'd just do:

thead() { head "$@" | cut -d, -f1- | column -s, -t; }

So you can do thead -n 12 file.csv file2.csv for instance.

share|improve this answer

answered 41 mins ago

Stéphane ChazelasStéphane Chazelas

306k57580935

add a comment | 

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4

For anything more advanced than a simple command, use a shell function instead of an alias:

thead () {

    head "$1" | cut -d, -f1- | column -s, -t

}

This shell function would run head on its first argument, and then send the result through the pipeline.

Or,

thead () {

    head "$2" | cut -d "$1" -f1- | column -s, -t

}

... to be able to use it as

thead ',' filename

Or even, to allow for an optional delimiter (and use comma if none is given),

thead () {

    local delim=','



    if [ "$#" -gt 1 ]; then

        delim=$1

        shift

    fi



    head "$1" | cut -d "$delim" -f1- | column -s, -t

}

The function definition above could be placed wherever you usually define aliases.

---

The issue with having a pipeline in an alias is that when you use the alias with an argument, this argument would be added to the end of the pipeline, not after the first command in the pipeline.

---

The bash manual contains the sentence

For almost every purpose, aliases are superseded by shell functions.

share|improve this answer

edited 23 mins ago

answered 1 hour ago

KusalanandaKusalananda

131k17250409

• 
  
  
  

  
  

  
  
  
  
  
  

  
  
  that's good, do you know btw how can I adjust it to accept a separator as a parameter to thead?
  
  – Max Li
  1 hour ago
  

  
  
  
  


• 
  
  
  

  
  

  
  
  
  
  
  

  
  
  @MaxLi See updated answer.
  
  – Kusalananda
  1 hour ago
  

  
  
  
  

add a comment | 

4

For anything more advanced than a simple command, use a shell function instead of an alias:

thead () {

    head "$1" | cut -d, -f1- | column -s, -t

}

This shell function would run head on its first argument, and then send the result through the pipeline.

Or,

thead () {

    head "$2" | cut -d "$1" -f1- | column -s, -t

}

... to be able to use it as

thead ',' filename

Or even, to allow for an optional delimiter (and use comma if none is given),

thead () {

    local delim=','



    if [ "$#" -gt 1 ]; then

        delim=$1

        shift

    fi



    head "$1" | cut -d "$delim" -f1- | column -s, -t

}

The function definition above could be placed wherever you usually define aliases.

---

The issue with having a pipeline in an alias is that when you use the alias with an argument, this argument would be added to the end of the pipeline, not after the first command in the pipeline.

---

The bash manual contains the sentence

For almost every purpose, aliases are superseded by shell functions.

share|improve this answer

edited 23 mins ago

answered 1 hour ago

KusalanandaKusalananda

131k17250409

• 
  
  
  

  
  

  
  
  
  
  
  

  
  
  that's good, do you know btw how can I adjust it to accept a separator as a parameter to thead?
  
  – Max Li
  1 hour ago
  

  
  
  
  


• 
  
  
  

  
  

  
  
  
  
  
  

  
  
  @MaxLi See updated answer.
  
  – Kusalananda
  1 hour ago
  

  
  
  
  

add a comment | 

For anything more advanced than a simple command, use a shell function instead of an alias:

thead () {

    head "$1" | cut -d, -f1- | column -s, -t

}

This shell function would run head on its first argument, and then send the result through the pipeline.

Or,

thead () {

    head "$2" | cut -d "$1" -f1- | column -s, -t

}

... to be able to use it as

thead ',' filename

Or even, to allow for an optional delimiter (and use comma if none is given),

thead () {

    local delim=','



    if [ "$#" -gt 1 ]; then

        delim=$1

        shift

    fi



    head "$1" | cut -d "$delim" -f1- | column -s, -t

}

The function definition above could be placed wherever you usually define aliases.

---

The issue with having a pipeline in an alias is that when you use the alias with an argument, this argument would be added to the end of the pipeline, not after the first command in the pipeline.

---

The bash manual contains the sentence

For almost every purpose, aliases are superseded by shell functions.

share|improve this answer

edited 23 mins ago

answered 1 hour ago

KusalanandaKusalananda

131k17250409

thead () {

    head "$1" | cut -d, -f1- | column -s, -t

}

thead () {

    head "$2" | cut -d "$1" -f1- | column -s, -t

}

thead ',' filename

thead () {

    local delim=','



    if [ "$#" -gt 1 ]; then

        delim=$1

        shift

    fi



    head "$1" | cut -d "$delim" -f1- | column -s, -t

}

share|improve this answer

edited 23 mins ago

answered 1 hour ago

KusalanandaKusalananda

131k17250409

answered 1 hour ago

KusalanandaKusalananda

131k17250409

answered 1 hour ago

KusalanandaKusalananda

131k17250409

2

alias expansion is just text substitution which is parsed again by the shell, so when you do:

thead file.csv

That's just replaced with:

head | cut -d, -f1- | column -s, -t file.csv

and interpreted again.

If you had written:

<file.csv thead

or

cat file.csv | thead

or

{ thead; } < file.csv

It would have worked as it would have been replaced with:

<file.csv head | cut -d, -f1- | column -s, -t

cat file.csv | head | cut -d, -f1- | column -s, -t

{ head | cut -d, -f1- | column -s, -t; } < file.csv

respectively. In any case, as @Kusalananda says, it's much better to use functions or scripts than aliases for that. Here, I'd just do:

thead() { head "$@" | cut -d, -f1- | column -s, -t; }

So you can do thead -n 12 file.csv file2.csv for instance.

share|improve this answer

answered 41 mins ago

Stéphane ChazelasStéphane Chazelas

306k57580935

add a comment | 

2

alias expansion is just text substitution which is parsed again by the shell, so when you do:

thead file.csv

That's just replaced with:

head | cut -d, -f1- | column -s, -t file.csv

and interpreted again.

If you had written:

<file.csv thead

or

cat file.csv | thead

or

{ thead; } < file.csv

It would have worked as it would have been replaced with:

<file.csv head | cut -d, -f1- | column -s, -t

cat file.csv | head | cut -d, -f1- | column -s, -t

{ head | cut -d, -f1- | column -s, -t; } < file.csv

respectively. In any case, as @Kusalananda says, it's much better to use functions or scripts than aliases for that. Here, I'd just do:

thead() { head "$@" | cut -d, -f1- | column -s, -t; }

So you can do thead -n 12 file.csv file2.csv for instance.

share|improve this answer

answered 41 mins ago

Stéphane ChazelasStéphane Chazelas

306k57580935

add a comment | 

alias expansion is just text substitution which is parsed again by the shell, so when you do:

thead file.csv

That's just replaced with:

head | cut -d, -f1- | column -s, -t file.csv

and interpreted again.

If you had written:

<file.csv thead

or

cat file.csv | thead

or

{ thead; } < file.csv

It would have worked as it would have been replaced with:

<file.csv head | cut -d, -f1- | column -s, -t

cat file.csv | head | cut -d, -f1- | column -s, -t

{ head | cut -d, -f1- | column -s, -t; } < file.csv

respectively. In any case, as @Kusalananda says, it's much better to use functions or scripts than aliases for that. Here, I'd just do:

thead() { head "$@" | cut -d, -f1- | column -s, -t; }

So you can do thead -n 12 file.csv file2.csv for instance.

share|improve this answer

answered 41 mins ago

Stéphane ChazelasStéphane Chazelas

306k57580935

thead file.csv

head | cut -d, -f1- | column -s, -t file.csv

<file.csv thead

cat file.csv | thead

{ thead; } < file.csv

<file.csv head | cut -d, -f1- | column -s, -t

cat file.csv | head | cut -d, -f1- | column -s, -t

{ head | cut -d, -f1- | column -s, -t; } < file.csv

thead() { head "$@" | cut -d, -f1- | column -s, -t; }

share|improve this answer

answered 41 mins ago

Stéphane ChazelasStéphane Chazelas

306k57580935

answered 41 mins ago

Stéphane ChazelasStéphane Chazelas

306k57580935

answered 41 mins ago

Stéphane ChazelasStéphane Chazelas

306k57580935