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Read line from file and process something

What is the difference between touch file and > file?How to replace a string of text with input from another filePrint only one line at a time from text fileReading lines from a text file and creating a text file for each name on each lineHow to squash all the contents of a multi-line file onto one line?Why does `read -r` still only get the first word of each line?Remove the first part of each line of a text fileRead from text1 and write to text2How to read line by line multiple filesSelect the remaining text in a line from a log fileread input from a file and append that values to variables using shell

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

3

There are multiple lines in my input file but my output file Token.csv only has one output line like this:

4TF16B7GA129E

4TF16B7GA129S

4TF16B7GA129D

4TF16B7GA129X

How to process every line?

My Code:

epoch=$(date -d "`date`" +"%s")

StringCsv="/home/Desktop/TokenGenScript/SerialNos.csv"

StringToken=b5242a2d7973c1aca3723c834ba0d239



while IFS=$'n' read -r line || [ -n "$line" ]

do

 j=$line

 serial=${j}:${epoch}:${StringToken}

 echo "$serial"|sha256sum > Token.csv

done < "$StringCsv"

command-line bash scripts

share

edited 16 hours ago

WinEunuuchs2Unix

48.7k1198187

asked 17 hours ago

Shubham AgrawalShubham Agrawal

191

New contributor

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

• 
  
  
  

  
  1
  

  
  
  
  
  
  

  
  
  and your code is not working or what is the problem? Btw, you don't need the doubled date.
  
  – RoVo
  17 hours ago
  

  
  
  
  

add a comment | 

3

There are multiple lines in my input file but my output file Token.csv only has one output line like this:

4TF16B7GA129E

4TF16B7GA129S

4TF16B7GA129D

4TF16B7GA129X

How to process every line?

My Code:

epoch=$(date -d "`date`" +"%s")

StringCsv="/home/Desktop/TokenGenScript/SerialNos.csv"

StringToken=b5242a2d7973c1aca3723c834ba0d239



while IFS=$'n' read -r line || [ -n "$line" ]

do

 j=$line

 serial=${j}:${epoch}:${StringToken}

 echo "$serial"|sha256sum > Token.csv

done < "$StringCsv"

command-line bash scripts

share

edited 16 hours ago

WinEunuuchs2Unix

48.7k1198187

asked 17 hours ago

Shubham AgrawalShubham Agrawal

191

New contributor

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

• 
  
  
  

  
  1
  

  
  
  
  
  
  

  
  
  and your code is not working or what is the problem? Btw, you don't need the doubled date.
  
  – RoVo
  17 hours ago
  

  
  
  
  

add a comment | 

There are multiple lines in my input file but my output file Token.csv only has one output line like this:

4TF16B7GA129E

4TF16B7GA129S

4TF16B7GA129D

4TF16B7GA129X

How to process every line?

My Code:

epoch=$(date -d "`date`" +"%s")

StringCsv="/home/Desktop/TokenGenScript/SerialNos.csv"

StringToken=b5242a2d7973c1aca3723c834ba0d239



while IFS=$'n' read -r line || [ -n "$line" ]

do

 j=$line

 serial=${j}:${epoch}:${StringToken}

 echo "$serial"|sha256sum > Token.csv

done < "$StringCsv"

command-line bash scripts

share

edited 16 hours ago

WinEunuuchs2Unix

48.7k1198187

asked 17 hours ago

Shubham AgrawalShubham Agrawal

191

New contributor

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

4TF16B7GA129E

4TF16B7GA129S

4TF16B7GA129D

4TF16B7GA129X

epoch=$(date -d "`date`" +"%s")

StringCsv="/home/Desktop/TokenGenScript/SerialNos.csv"

StringToken=b5242a2d7973c1aca3723c834ba0d239



while IFS=$'n' read -r line || [ -n "$line" ]

do

 j=$line

 serial=${j}:${epoch}:${StringToken}

 echo "$serial"|sha256sum > Token.csv

done < "$StringCsv"

share

edited 16 hours ago

WinEunuuchs2Unix

48.7k1198187

asked 17 hours ago

Shubham AgrawalShubham Agrawal

191

New contributor

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

share

edited 16 hours ago

WinEunuuchs2Unix

48.7k1198187

asked 17 hours ago

Shubham AgrawalShubham Agrawal

191

New contributor

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

edited 16 hours ago

WinEunuuchs2Unix

48.7k1198187

edited 16 hours ago

WinEunuuchs2Unix

48.7k1198187

asked 17 hours ago

Shubham AgrawalShubham Agrawal

191

New contributor

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

asked 17 hours ago

Shubham AgrawalShubham Agrawal

191

4 Answers
4

active

oldest

votes

4

Put the output redirection on the entire loop, not just the sha256sum command. Every time you redirect, you're recreating the output file from scratch. This will just create it once, and write to it repeatedly within the loop.

while IFS=$'n' read -r line || [ -n "$line" ]

do

 j=$line

 serial=${j}:${epoch}:${StringToken}

 echo "$serial"|sha256sum

done < "$StringCsv" > Token.csv

share|improve this answer

answered 12 hours ago

BarmarBarmar

1756

add a comment | 

4

You are writing to a file in a loop with this command:

echo "$serial"|sha256sum > Token.csv

However each time you loop you are erasing the file and writing a new entry. What you want to do is append (add to) the file each time you loop with this command:

echo "$serial"|sha256sum >> Token.csv

A single > tells bash to erase the file Token.csv and write the contents. A double >> tells bash to add to the end of the file.

---

The bash script would now look like this:

!/bin/bash

epoch=$(date -d "`date`" +"%s")

StringCsv="/home/Desktop/TokenGenScript/SerialNos.csv"

StringToken=b5242a2d7973c1aca3723c834ba0d239



> Token.csv # Empty file from last run



while IFS=$'n' read -r line || [ -n "$line" ]

do

 j=$line

 serial=${j}:${epoch}:${StringToken}

 echo "$serial"|sha256sum >> Token.csv # Append new record to end

done < "$StringCsv"

There are two ways to empty the file > Token.csv as used above and touch Token.csv. See:

• What is the difference between touch file and > file?

share|improve this answer

edited 2 hours ago

answered 16 hours ago

WinEunuuchs2UnixWinEunuuchs2Unix

48.7k1198187

• 
  
  
  

  
  

  
  
  
  
  
  

  
  
  There should probably be an explicit removal/truncation of Token.csv prior to the loop, to assure this run doesn't append to any existing file contents.
  
  – Monty Harder
  13 hours ago
  

  
  
  
  

add a comment | 

0

Use the command below for reading n lines from file:

head -n 1 filename

to write it to variable use this:

var=$(head -n 1 filename);

Or you can read nth line from file:

sed -n '2p' filename

The comand above will return second line of file. For your example you can use this:
sed -n $i'p' filename
where i is index.

BUT, for your code you need an index that will increase every iteration.

share|improve this answer

edited 11 hours ago

answered 11 hours ago

Vlad GavriukVlad Gavriuk

1113

New contributor

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

add a comment | 

0

Taking Why is using a shell loop to process text considered bad practice? way too seriously, and using GNU Awk's getline from a Coprocess:

gawk -v stringToken=b5242a2d7973c1aca3723c834ba0d239 '

  BEGIN{cmd="sha256sum"; s = systime()} 

  {

    print $0 s stringToken |& cmd; close(cmd,"to"); 

    cmd |& getline; close(cmd,"from")

  } 1

' SerialNos.csv > Token.csv

share|improve this answer

answered 9 hours ago

steeldriversteeldriver

71.4k11115187

add a comment | 

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4

Put the output redirection on the entire loop, not just the sha256sum command. Every time you redirect, you're recreating the output file from scratch. This will just create it once, and write to it repeatedly within the loop.

while IFS=$'n' read -r line || [ -n "$line" ]

do

 j=$line

 serial=${j}:${epoch}:${StringToken}

 echo "$serial"|sha256sum

done < "$StringCsv" > Token.csv

share|improve this answer

answered 12 hours ago

BarmarBarmar

1756

add a comment | 

4

Put the output redirection on the entire loop, not just the sha256sum command. Every time you redirect, you're recreating the output file from scratch. This will just create it once, and write to it repeatedly within the loop.

while IFS=$'n' read -r line || [ -n "$line" ]

do

 j=$line

 serial=${j}:${epoch}:${StringToken}

 echo "$serial"|sha256sum

done < "$StringCsv" > Token.csv

share|improve this answer

answered 12 hours ago

BarmarBarmar

1756

add a comment | 

Put the output redirection on the entire loop, not just the sha256sum command. Every time you redirect, you're recreating the output file from scratch. This will just create it once, and write to it repeatedly within the loop.

while IFS=$'n' read -r line || [ -n "$line" ]

do

 j=$line

 serial=${j}:${epoch}:${StringToken}

 echo "$serial"|sha256sum

done < "$StringCsv" > Token.csv

share|improve this answer

answered 12 hours ago

BarmarBarmar

1756

while IFS=$'n' read -r line || [ -n "$line" ]

do

 j=$line

 serial=${j}:${epoch}:${StringToken}

 echo "$serial"|sha256sum

done < "$StringCsv" > Token.csv

share|improve this answer

answered 12 hours ago

BarmarBarmar

1756

answered 12 hours ago

BarmarBarmar

1756

answered 12 hours ago

BarmarBarmar

1756

4

You are writing to a file in a loop with this command:

echo "$serial"|sha256sum > Token.csv

However each time you loop you are erasing the file and writing a new entry. What you want to do is append (add to) the file each time you loop with this command:

echo "$serial"|sha256sum >> Token.csv

A single > tells bash to erase the file Token.csv and write the contents. A double >> tells bash to add to the end of the file.

---

The bash script would now look like this:

!/bin/bash

epoch=$(date -d "`date`" +"%s")

StringCsv="/home/Desktop/TokenGenScript/SerialNos.csv"

StringToken=b5242a2d7973c1aca3723c834ba0d239



> Token.csv # Empty file from last run



while IFS=$'n' read -r line || [ -n "$line" ]

do

 j=$line

 serial=${j}:${epoch}:${StringToken}

 echo "$serial"|sha256sum >> Token.csv # Append new record to end

done < "$StringCsv"

There are two ways to empty the file > Token.csv as used above and touch Token.csv. See:

• What is the difference between touch file and > file?

share|improve this answer

edited 2 hours ago

answered 16 hours ago

WinEunuuchs2UnixWinEunuuchs2Unix

48.7k1198187

• 
  
  
  

  
  

  
  
  
  
  
  

  
  
  There should probably be an explicit removal/truncation of Token.csv prior to the loop, to assure this run doesn't append to any existing file contents.
  
  – Monty Harder
  13 hours ago
  

  
  
  
  

add a comment | 

4

You are writing to a file in a loop with this command:

echo "$serial"|sha256sum > Token.csv

However each time you loop you are erasing the file and writing a new entry. What you want to do is append (add to) the file each time you loop with this command:

echo "$serial"|sha256sum >> Token.csv

A single > tells bash to erase the file Token.csv and write the contents. A double >> tells bash to add to the end of the file.

---

The bash script would now look like this:

!/bin/bash

epoch=$(date -d "`date`" +"%s")

StringCsv="/home/Desktop/TokenGenScript/SerialNos.csv"

StringToken=b5242a2d7973c1aca3723c834ba0d239



> Token.csv # Empty file from last run



while IFS=$'n' read -r line || [ -n "$line" ]

do

 j=$line

 serial=${j}:${epoch}:${StringToken}

 echo "$serial"|sha256sum >> Token.csv # Append new record to end

done < "$StringCsv"

There are two ways to empty the file > Token.csv as used above and touch Token.csv. See:

• What is the difference between touch file and > file?

share|improve this answer

edited 2 hours ago

answered 16 hours ago

WinEunuuchs2UnixWinEunuuchs2Unix

48.7k1198187

• 
  
  
  

  
  

  
  
  
  
  
  

  
  
  There should probably be an explicit removal/truncation of Token.csv prior to the loop, to assure this run doesn't append to any existing file contents.
  
  – Monty Harder
  13 hours ago
  

  
  
  
  

add a comment | 

You are writing to a file in a loop with this command:

echo "$serial"|sha256sum > Token.csv

However each time you loop you are erasing the file and writing a new entry. What you want to do is append (add to) the file each time you loop with this command:

echo "$serial"|sha256sum >> Token.csv

A single > tells bash to erase the file Token.csv and write the contents. A double >> tells bash to add to the end of the file.

---

The bash script would now look like this:

!/bin/bash

epoch=$(date -d "`date`" +"%s")

StringCsv="/home/Desktop/TokenGenScript/SerialNos.csv"

StringToken=b5242a2d7973c1aca3723c834ba0d239



> Token.csv # Empty file from last run



while IFS=$'n' read -r line || [ -n "$line" ]

do

 j=$line

 serial=${j}:${epoch}:${StringToken}

 echo "$serial"|sha256sum >> Token.csv # Append new record to end

done < "$StringCsv"

There are two ways to empty the file > Token.csv as used above and touch Token.csv. See:

• What is the difference between touch file and > file?

share|improve this answer

edited 2 hours ago

answered 16 hours ago

WinEunuuchs2UnixWinEunuuchs2Unix

48.7k1198187

echo "$serial"|sha256sum > Token.csv

echo "$serial"|sha256sum >> Token.csv

!/bin/bash

epoch=$(date -d "`date`" +"%s")

StringCsv="/home/Desktop/TokenGenScript/SerialNos.csv"

StringToken=b5242a2d7973c1aca3723c834ba0d239



> Token.csv # Empty file from last run



while IFS=$'n' read -r line || [ -n "$line" ]

do

 j=$line

 serial=${j}:${epoch}:${StringToken}

 echo "$serial"|sha256sum >> Token.csv # Append new record to end

done < "$StringCsv"

share|improve this answer

edited 2 hours ago

answered 16 hours ago

WinEunuuchs2UnixWinEunuuchs2Unix

48.7k1198187

answered 16 hours ago

WinEunuuchs2UnixWinEunuuchs2Unix

48.7k1198187

answered 16 hours ago

WinEunuuchs2UnixWinEunuuchs2Unix

48.7k1198187

0

Use the command below for reading n lines from file:

head -n 1 filename

to write it to variable use this:

var=$(head -n 1 filename);

Or you can read nth line from file:

sed -n '2p' filename

The comand above will return second line of file. For your example you can use this:
sed -n $i'p' filename
where i is index.

BUT, for your code you need an index that will increase every iteration.

share|improve this answer

edited 11 hours ago

answered 11 hours ago

Vlad GavriukVlad Gavriuk

1113

New contributor

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

add a comment | 

0

Use the command below for reading n lines from file:

head -n 1 filename

to write it to variable use this:

var=$(head -n 1 filename);

Or you can read nth line from file:

sed -n '2p' filename

The comand above will return second line of file. For your example you can use this:
sed -n $i'p' filename
where i is index.

BUT, for your code you need an index that will increase every iteration.

share|improve this answer

edited 11 hours ago

answered 11 hours ago

Vlad GavriukVlad Gavriuk

1113

New contributor

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

add a comment | 

Use the command below for reading n lines from file:

head -n 1 filename

to write it to variable use this:

var=$(head -n 1 filename);

Or you can read nth line from file:

sed -n '2p' filename

The comand above will return second line of file. For your example you can use this:
sed -n $i'p' filename
where i is index.

BUT, for your code you need an index that will increase every iteration.

share|improve this answer

edited 11 hours ago

answered 11 hours ago

Vlad GavriukVlad Gavriuk

1113

New contributor

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

head -n 1 filename

var=$(head -n 1 filename);

sed -n '2p' filename

share|improve this answer

edited 11 hours ago

answered 11 hours ago

Vlad GavriukVlad Gavriuk

1113

New contributor

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

answered 11 hours ago

Vlad GavriukVlad Gavriuk

1113

New contributor

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

answered 11 hours ago

Vlad GavriukVlad Gavriuk

1113

0

Taking Why is using a shell loop to process text considered bad practice? way too seriously, and using GNU Awk's getline from a Coprocess:

gawk -v stringToken=b5242a2d7973c1aca3723c834ba0d239 '

  BEGIN{cmd="sha256sum"; s = systime()} 

  {

    print $0 s stringToken |& cmd; close(cmd,"to"); 

    cmd |& getline; close(cmd,"from")

  } 1

' SerialNos.csv > Token.csv

share|improve this answer

answered 9 hours ago

steeldriversteeldriver

71.4k11115187

add a comment | 

0

Taking Why is using a shell loop to process text considered bad practice? way too seriously, and using GNU Awk's getline from a Coprocess:

gawk -v stringToken=b5242a2d7973c1aca3723c834ba0d239 '

  BEGIN{cmd="sha256sum"; s = systime()} 

  {

    print $0 s stringToken |& cmd; close(cmd,"to"); 

    cmd |& getline; close(cmd,"from")

  } 1

' SerialNos.csv > Token.csv

share|improve this answer

answered 9 hours ago

steeldriversteeldriver

71.4k11115187

add a comment | 

Taking Why is using a shell loop to process text considered bad practice? way too seriously, and using GNU Awk's getline from a Coprocess:

gawk -v stringToken=b5242a2d7973c1aca3723c834ba0d239 '

  BEGIN{cmd="sha256sum"; s = systime()} 

  {

    print $0 s stringToken |& cmd; close(cmd,"to"); 

    cmd |& getline; close(cmd,"from")

  } 1

' SerialNos.csv > Token.csv

share|improve this answer

answered 9 hours ago

steeldriversteeldriver

71.4k11115187

gawk -v stringToken=b5242a2d7973c1aca3723c834ba0d239 '

  BEGIN{cmd="sha256sum"; s = systime()} 

  {

    print $0 s stringToken |& cmd; close(cmd,"to"); 

    cmd |& getline; close(cmd,"from")

  } 1

' SerialNos.csv > Token.csv

share|improve this answer

answered 9 hours ago

steeldriversteeldriver

71.4k11115187

answered 9 hours ago

steeldriversteeldriver

71.4k11115187

answered 9 hours ago

steeldriversteeldriver

71.4k11115187