Reading from a text file and printing the words character by character at a time

up vote
5
down vote

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I would like to write a program that reads from a text file and prints in Terminal the words of that file character by character every one second.

For example, in a text file log.txt let's say I have this sentence:

I love Unix but I don't know programming.

I would like the code to read the previous sentence and print the letters, the spaces one by one every second.

edited Sep 8 at 21:15

don_crissti

47k15124154

asked Sep 8 at 20:07

Zahi

636

New contributor

add a commentÂ |Â

up vote
5
down vote

favorite

I would like to write a program that reads from a text file and prints in Terminal the words of that file character by character every one second.

For example, in a text file log.txt let's say I have this sentence:

I love Unix but I don't know programming.

I would like the code to read the previous sentence and print the letters, the spaces one by one every second.

edited Sep 8 at 21:15

don_crissti

47k15124154

asked Sep 8 at 20:07

Zahi

636

New contributor

add a commentÂ |Â

up vote
5
down vote

favorite

I would like to write a program that reads from a text file and prints in Terminal the words of that file character by character every one second.

For example, in a text file log.txt let's say I have this sentence:

I love Unix but I don't know programming.

I would like the code to read the previous sentence and print the letters, the spaces one by one every second.

edited Sep 8 at 21:15

don_crissti

47k15124154

asked Sep 8 at 20:07

Zahi

636

New contributor

I would like to write a program that reads from a text file and prints in Terminal the words of that file character by character every one second.

For example, in a text file log.txt let's say I have this sentence:

I love Unix but I don't know programming.

I would like the code to read the previous sentence and print the letters, the spaces one by one every second.

shell text-processing

edited Sep 8 at 21:15

don_crissti

47k15124154

asked Sep 8 at 20:07

Zahi

636

New contributor

edited Sep 8 at 21:15

don_crissti

47k15124154

asked Sep 8 at 20:07

Zahi

636

New contributor

edited Sep 8 at 21:15

don_crissti

47k15124154

edited Sep 8 at 21:15

don_crissti

47k15124154

edited Sep 8 at 21:15

don_crissti

47k15124154

asked Sep 8 at 20:07

Zahi

636

New contributor

asked Sep 8 at 20:07

Zahi

636

asked Sep 8 at 20:07

Zahi

636

New contributor

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

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5 Answers
5

active

oldest

votes

up vote
6
down vote

accepted

You can do this

var=$(cat log.txt)
for (( i=0; i<$#var; i++ )); do
 sleep 1 | echo -ne "$var:$i:1"
done
echo ""

edited Sep 8 at 21:08

answered Sep 8 at 20:10

Goro

1,40641643

thk for quick answr. this is wht i want but why it priunt on the same line ike this `I love Unix but I don't know programming.[zahi@sonar]$, how print on separate line?
â€“Â Zahi
Sep 8 at 20:30

Ah, please see my revisions
â€“Â Goro
Sep 8 at 20:32

thank you very much
â€“Â Zahi
Sep 8 at 20:34

add a commentÂ |Â

up vote
9
down vote

Goro's answer will work, but it should be noted that command substitution removes trailing newlines as specified by POSIX standard. Thus it may not be desirable where you want to actually iterate over all charactes, even non-printable ones. Another issue is that C-style for loop is used in bash and ksh93, but not in standard (aka POSIX-comliant ) /bin/sh. The $variable:index:offset form of parameter expansion is also type of bashism and not specified by POSIX definitions of parameter expansion (though supported by ksh93 and zsh).

Nonetheless, there's a way to iterate over all characters in file portably and in a far more practical way. That's to use awk:

# all characters on the same line
$ awk 'for(i=1;i<=length;i++) printf "%c",substr($0,i,1); system("sleep 1");; print' input.txt

# all characters on separate lines
$ awk 'for(i=1;i<=length;i++) print substr($0, i, 1); system("sleep 1"); ' input.txt

With this command substr() and system() are both specified in POSIX awk and will in fact iterate over all characters.

edited Sep 8 at 21:33

answered Sep 8 at 21:12

Sergiy Kolodyazhnyy

7,92011648

1

@Goro Already added a comment about that, see the edit
â€“Â Sergiy Kolodyazhnyy
Sep 8 at 21:15

3

Very elegant!! thanks! ;-)
â€“Â Goro
Sep 8 at 21:20

2

@don_crissti I need to find a better phrase than "bashism" because I always get ksh and zsh mentioned. Can we start using something like ba,k,zsh maybe ? :)
â€“Â Sergiy Kolodyazhnyy
Sep 8 at 21:33

2

I think just mentioning non-posix or non-standard would do...
â€“Â don_crissti
Sep 8 at 21:33

@don_crissti non-posix adds another level of ambiguity because POSIX mostly was based on ksh and Bourne shell, and bash has --posix flag and supoorts most of the POSIX features. Idk, there's gotta be a better way to phrase it
â€“Â Sergiy Kolodyazhnyy
Sep 9 at 0:28

Â |Â
show 1 more comment

up vote
3
down vote

With bash or ksh93 you can read single characters using the shell's built-in read command:

while IFS= read -r -n 1 c; do 
 printf '%c' "$c"
 sleep 1
done < log.txt
printf 'n'

answered Sep 8 at 22:46

steeldriver

32.1k34979

add a commentÂ |Â

up vote
1
down vote

Here's a Python solution:

python -c "from time import sleep
with open('/tmp/file.txt') as f:
 for line in f:
 for c in line:
 print(c, end='', flush=True);sleep(1);"

You should just be able to paste that on the command line and change the name of the input file.

answered Sep 9 at 3:32

user1717828

1,60611125

add a commentÂ |Â

up vote
0
down vote

You could do this with Perl as shown:

perl -pe 'BEGIN=1; sleep 1' log.txt

-p will autoprint the current record before fetching the next.

$/=1 will make perl read the input stream a byte at a time, and assuming the characters are a byte sized.

$|=1 will output is buffered.

answered 2 days ago

Rakesh Sharma

53013

add a commentÂ |Â

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5 Answers
5

active

oldest

votes

5 Answers
5

active

oldest

votes

up vote
6
down vote

accepted

You can do this

var=$(cat log.txt)
for (( i=0; i<$#var; i++ )); do
 sleep 1 | echo -ne "$var:$i:1"
done
echo ""

edited Sep 8 at 21:08

answered Sep 8 at 20:10

Goro

1,40641643

thk for quick answr. this is wht i want but why it priunt on the same line ike this `I love Unix but I don't know programming.[zahi@sonar]$, how print on separate line?
â€“Â Zahi
Sep 8 at 20:30

Ah, please see my revisions
â€“Â Goro
Sep 8 at 20:32

thank you very much
â€“Â Zahi
Sep 8 at 20:34

add a commentÂ |Â

up vote
6
down vote

accepted

You can do this

var=$(cat log.txt)
for (( i=0; i<$#var; i++ )); do
 sleep 1 | echo -ne "$var:$i:1"
done
echo ""

edited Sep 8 at 21:08

answered Sep 8 at 20:10

Goro

1,40641643

thk for quick answr. this is wht i want but why it priunt on the same line ike this `I love Unix but I don't know programming.[zahi@sonar]$, how print on separate line?
â€“Â Zahi
Sep 8 at 20:30

Ah, please see my revisions
â€“Â Goro
Sep 8 at 20:32

thank you very much
â€“Â Zahi
Sep 8 at 20:34

add a commentÂ |Â

up vote
6
down vote

accepted

You can do this

var=$(cat log.txt)
for (( i=0; i<$#var; i++ )); do
 sleep 1 | echo -ne "$var:$i:1"
done
echo ""

edited Sep 8 at 21:08

answered Sep 8 at 20:10

Goro

1,40641643

You can do this

var=$(cat log.txt)
for (( i=0; i<$#var; i++ )); do
 sleep 1 | echo -ne "$var:$i:1"
done
echo ""

edited Sep 8 at 21:08

answered Sep 8 at 20:10

Goro

1,40641643

edited Sep 8 at 21:08

answered Sep 8 at 20:10

Goro

1,40641643

answered Sep 8 at 20:10

Goro

1,40641643

answered Sep 8 at 20:10

Goro

1,40641643

thk for quick answr. this is wht i want but why it priunt on the same line ike this `I love Unix but I don't know programming.[zahi@sonar]$, how print on separate line?
â€“Â Zahi
Sep 8 at 20:30

Ah, please see my revisions
â€“Â Goro
Sep 8 at 20:32

thank you very much
â€“Â Zahi
Sep 8 at 20:34

add a commentÂ |Â

thk for quick answr. this is wht i want but why it priunt on the same line ike this `I love Unix but I don't know programming.[zahi@sonar]$, how print on separate line?
â€“Â Zahi
Sep 8 at 20:30

Ah, please see my revisions
â€“Â Goro
Sep 8 at 20:32

thank you very much
â€“Â Zahi
Sep 8 at 20:34

thk for quick answr. this is wht i want but why it priunt on the same line ike this `I love Unix but I don't know programming.[zahi@sonar]$, how print on separate line?
â€“Â Zahi
Sep 8 at 20:30

Ah, please see my revisions
â€“Â Goro
Sep 8 at 20:32

thank you very much
â€“Â Zahi
Sep 8 at 20:34

add a commentÂ |Â

up vote
9
down vote

Nonetheless, there's a way to iterate over all characters in file portably and in a far more practical way. That's to use awk:

# all characters on the same line
$ awk 'for(i=1;i<=length;i++) printf "%c",substr($0,i,1); system("sleep 1");; print' input.txt

# all characters on separate lines
$ awk 'for(i=1;i<=length;i++) print substr($0, i, 1); system("sleep 1"); ' input.txt

With this command substr() and system() are both specified in POSIX awk and will in fact iterate over all characters.

edited Sep 8 at 21:33

answered Sep 8 at 21:12

Sergiy Kolodyazhnyy

7,92011648

1

@Goro Already added a comment about that, see the edit
â€“Â Sergiy Kolodyazhnyy
Sep 8 at 21:15

3

Very elegant!! thanks! ;-)
â€“Â Goro
Sep 8 at 21:20

2

@don_crissti I need to find a better phrase than "bashism" because I always get ksh and zsh mentioned. Can we start using something like ba,k,zsh maybe ? :)
â€“Â Sergiy Kolodyazhnyy
Sep 8 at 21:33

2

I think just mentioning non-posix or non-standard would do...
â€“Â don_crissti
Sep 8 at 21:33

@don_crissti non-posix adds another level of ambiguity because POSIX mostly was based on ksh and Bourne shell, and bash has --posix flag and supoorts most of the POSIX features. Idk, there's gotta be a better way to phrase it
â€“Â Sergiy Kolodyazhnyy
Sep 9 at 0:28

Â |Â
show 1 more comment

up vote
9
down vote

Nonetheless, there's a way to iterate over all characters in file portably and in a far more practical way. That's to use awk:

# all characters on the same line
$ awk 'for(i=1;i<=length;i++) printf "%c",substr($0,i,1); system("sleep 1");; print' input.txt

# all characters on separate lines
$ awk 'for(i=1;i<=length;i++) print substr($0, i, 1); system("sleep 1"); ' input.txt

With this command substr() and system() are both specified in POSIX awk and will in fact iterate over all characters.

edited Sep 8 at 21:33

answered Sep 8 at 21:12

Sergiy Kolodyazhnyy

7,92011648

1

@Goro Already added a comment about that, see the edit
â€“Â Sergiy Kolodyazhnyy
Sep 8 at 21:15

3

Very elegant!! thanks! ;-)
â€“Â Goro
Sep 8 at 21:20

2

@don_crissti I need to find a better phrase than "bashism" because I always get ksh and zsh mentioned. Can we start using something like ba,k,zsh maybe ? :)
â€“Â Sergiy Kolodyazhnyy
Sep 8 at 21:33

2

I think just mentioning non-posix or non-standard would do...
â€“Â don_crissti
Sep 8 at 21:33

@don_crissti non-posix adds another level of ambiguity because POSIX mostly was based on ksh and Bourne shell, and bash has --posix flag and supoorts most of the POSIX features. Idk, there's gotta be a better way to phrase it
â€“Â Sergiy Kolodyazhnyy
Sep 9 at 0:28

Â |Â
show 1 more comment

up vote
9
down vote

Nonetheless, there's a way to iterate over all characters in file portably and in a far more practical way. That's to use awk:

# all characters on the same line
$ awk 'for(i=1;i<=length;i++) printf "%c",substr($0,i,1); system("sleep 1");; print' input.txt

# all characters on separate lines
$ awk 'for(i=1;i<=length;i++) print substr($0, i, 1); system("sleep 1"); ' input.txt

With this command substr() and system() are both specified in POSIX awk and will in fact iterate over all characters.

edited Sep 8 at 21:33

answered Sep 8 at 21:12

Sergiy Kolodyazhnyy

7,92011648

Nonetheless, there's a way to iterate over all characters in file portably and in a far more practical way. That's to use awk:

# all characters on the same line
$ awk 'for(i=1;i<=length;i++) printf "%c",substr($0,i,1); system("sleep 1");; print' input.txt

# all characters on separate lines
$ awk 'for(i=1;i<=length;i++) print substr($0, i, 1); system("sleep 1"); ' input.txt

With this command substr() and system() are both specified in POSIX awk and will in fact iterate over all characters.

edited Sep 8 at 21:33

answered Sep 8 at 21:12

Sergiy Kolodyazhnyy

7,92011648

edited Sep 8 at 21:33

answered Sep 8 at 21:12

Sergiy Kolodyazhnyy

7,92011648

answered Sep 8 at 21:12

Sergiy Kolodyazhnyy

7,92011648

answered Sep 8 at 21:12

Sergiy Kolodyazhnyy

7,92011648

1

@Goro Already added a comment about that, see the edit
â€“Â Sergiy Kolodyazhnyy
Sep 8 at 21:15

3

Very elegant!! thanks! ;-)
â€“Â Goro
Sep 8 at 21:20

2

@don_crissti I need to find a better phrase than "bashism" because I always get ksh and zsh mentioned. Can we start using something like ba,k,zsh maybe ? :)
â€“Â Sergiy Kolodyazhnyy
Sep 8 at 21:33

2

I think just mentioning non-posix or non-standard would do...
â€“Â don_crissti
Sep 8 at 21:33

@don_crissti non-posix adds another level of ambiguity because POSIX mostly was based on ksh and Bourne shell, and bash has --posix flag and supoorts most of the POSIX features. Idk, there's gotta be a better way to phrase it
â€“Â Sergiy Kolodyazhnyy
Sep 9 at 0:28

Â |Â
show 1 more comment

1

@Goro Already added a comment about that, see the edit
â€“Â Sergiy Kolodyazhnyy
Sep 8 at 21:15

3

Very elegant!! thanks! ;-)
â€“Â Goro
Sep 8 at 21:20

2

@don_crissti I need to find a better phrase than "bashism" because I always get ksh and zsh mentioned. Can we start using something like ba,k,zsh maybe ? :)
â€“Â Sergiy Kolodyazhnyy
Sep 8 at 21:33

2

I think just mentioning non-posix or non-standard would do...
â€“Â don_crissti
Sep 8 at 21:33

@don_crissti non-posix adds another level of ambiguity because POSIX mostly was based on ksh and Bourne shell, and bash has --posix flag and supoorts most of the POSIX features. Idk, there's gotta be a better way to phrase it
â€“Â Sergiy Kolodyazhnyy
Sep 9 at 0:28

@Goro Already added a comment about that, see the edit
â€“Â Sergiy Kolodyazhnyy
Sep 8 at 21:15

Very elegant!! thanks! ;-)
â€“Â Goro
Sep 8 at 21:20

@don_crissti I need to find a better phrase than "bashism" because I always get ksh and zsh mentioned. Can we start using something like ba,k,zsh maybe ? :)
â€“Â Sergiy Kolodyazhnyy
Sep 8 at 21:33

I think just mentioning non-posix or non-standard would do...
â€“Â don_crissti
Sep 8 at 21:33

@don_crissti non-posix adds another level of ambiguity because POSIX mostly was based on ksh and Bourne shell, and bash has --posix flag and supoorts most of the POSIX features. Idk, there's gotta be a better way to phrase it
â€“Â Sergiy Kolodyazhnyy
Sep 9 at 0:28

Â |Â
show 1 more comment

up vote
3
down vote

With bash or ksh93 you can read single characters using the shell's built-in read command:

while IFS= read -r -n 1 c; do 
 printf '%c' "$c"
 sleep 1
done < log.txt
printf 'n'

answered Sep 8 at 22:46

steeldriver

32.1k34979

add a commentÂ |Â

up vote
3
down vote

With bash or ksh93 you can read single characters using the shell's built-in read command:

while IFS= read -r -n 1 c; do 
 printf '%c' "$c"
 sleep 1
done < log.txt
printf 'n'

answered Sep 8 at 22:46

steeldriver

32.1k34979

add a commentÂ |Â

up vote
3
down vote

With bash or ksh93 you can read single characters using the shell's built-in read command:

while IFS= read -r -n 1 c; do 
 printf '%c' "$c"
 sleep 1
done < log.txt
printf 'n'

answered Sep 8 at 22:46

steeldriver

32.1k34979

With bash or ksh93 you can read single characters using the shell's built-in read command:

while IFS= read -r -n 1 c; do 
 printf '%c' "$c"
 sleep 1
done < log.txt
printf 'n'

answered Sep 8 at 22:46

steeldriver

32.1k34979

answered Sep 8 at 22:46

steeldriver

32.1k34979

answered Sep 8 at 22:46

steeldriver

32.1k34979

answered Sep 8 at 22:46

steeldriver

32.1k34979

add a commentÂ |Â

up vote
1
down vote

Here's a Python solution:

python -c "from time import sleep
with open('/tmp/file.txt') as f:
 for line in f:
 for c in line:
 print(c, end='', flush=True);sleep(1);"

You should just be able to paste that on the command line and change the name of the input file.

answered Sep 9 at 3:32

user1717828

1,60611125

add a commentÂ |Â

up vote
1
down vote

Here's a Python solution:

python -c "from time import sleep
with open('/tmp/file.txt') as f:
 for line in f:
 for c in line:
 print(c, end='', flush=True);sleep(1);"

You should just be able to paste that on the command line and change the name of the input file.

answered Sep 9 at 3:32

user1717828

1,60611125

add a commentÂ |Â

up vote
1
down vote

Here's a Python solution:

python -c "from time import sleep
with open('/tmp/file.txt') as f:
 for line in f:
 for c in line:
 print(c, end='', flush=True);sleep(1);"

You should just be able to paste that on the command line and change the name of the input file.

answered Sep 9 at 3:32

user1717828

1,60611125

Here's a Python solution:

python -c "from time import sleep
with open('/tmp/file.txt') as f:
 for line in f:
 for c in line:
 print(c, end='', flush=True);sleep(1);"

You should just be able to paste that on the command line and change the name of the input file.

answered Sep 9 at 3:32

user1717828

1,60611125

answered Sep 9 at 3:32

user1717828

1,60611125

answered Sep 9 at 3:32

user1717828

1,60611125

answered Sep 9 at 3:32

user1717828

1,60611125

add a commentÂ |Â

up vote
0
down vote

You could do this with Perl as shown:

perl -pe 'BEGIN=1; sleep 1' log.txt

-p will autoprint the current record before fetching the next.

$/=1 will make perl read the input stream a byte at a time, and assuming the characters are a byte sized.

$|=1 will output is buffered.

answered 2 days ago

Rakesh Sharma

53013

add a commentÂ |Â

up vote
0
down vote

You could do this with Perl as shown:

perl -pe 'BEGIN=1; sleep 1' log.txt

-p will autoprint the current record before fetching the next.

$/=1 will make perl read the input stream a byte at a time, and assuming the characters are a byte sized.

$|=1 will output is buffered.

answered 2 days ago

Rakesh Sharma

53013

add a commentÂ |Â

up vote
0
down vote

You could do this with Perl as shown:

perl -pe 'BEGIN=1; sleep 1' log.txt

-p will autoprint the current record before fetching the next.

$/=1 will make perl read the input stream a byte at a time, and assuming the characters are a byte sized.

$|=1 will output is buffered.

answered 2 days ago

Rakesh Sharma

53013

You could do this with Perl as shown:

perl -pe 'BEGIN=1; sleep 1' log.txt

-p will autoprint the current record before fetching the next.

$/=1 will make perl read the input stream a byte at a time, and assuming the characters are a byte sized.

$|=1 will output is buffered.

answered 2 days ago

Rakesh Sharma

53013

answered 2 days ago

Rakesh Sharma

53013

answered 2 days ago

Rakesh Sharma

53013

answered 2 days ago

Rakesh Sharma

53013

add a commentÂ |Â

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

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