Can i read a file character by character - Shell Programming and Scripting

karnan · #1 (**permalink**) 11-20-2007

How to read character by character using awk

Ygor · #2 (**permalink**) 11-20-2007

Either use fold -1 then pipe into awk, or loop through each character in awk, e.g....

Code:

$ cat file1
abc
$ fold -1 file1 | awk '{print $0}'
a
b
c
$ awk '{for(i=1;i<=length;i++) print substr($0, i, 1)}' file1
a
b
c

LivinFree · #3 (**permalink**) 11-20-2007

What shell? Bash has the `read` builtin where you can do:

Code:

while read -n1 char; do
 #do something with the byte in $char
done <input.file

srikanthg · #4 (**permalink**) 05-15-2008

could u explain what is "-n1" here in this syntax

Quote:

Originally Posted by LivinFree

What shell? Bash has the `read` builtin where you can do:

Code:

while read -n1 char; do
 #do something with the byte in $char
done <input.file

chella · #5 (**permalink**) 05-16-2008

Quote:

read -n nchars
Read returns after reading nchars characters rather than
waiting for a complete line of input.

So -n1 means reading character by character.

Regards,
Chella

srikanthg · #6 (**permalink**) 05-18-2008

what exactly the "number 1" do in the syntax

if i give 2 what will happen .... does it read 2 chars at a time

can u explain it little bit clear

regards
srikanth

era · #7 (**permalink**) 05-18-2008

Bash has a manual page and a built-in help system.

Code:

bash$ help read
...
If -n is supplied with a non-zero NCHARS argument, read returns after NCHARS
characters have been read.

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