Bash how to get text in file [closed] - bash

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I file /tmp/txt
contents of the file: aaa aaa aaa _bbb bbb bbb
I need to save the file /tmp/txt_left: aaa aaa aaa
I need to save the file /tmp/txt_right: bbb bbb bbb
!!! attention seeking solutions without the use of variables !!!

Answer 1

awk -F '_' '{print $1> "/tmp/txt_left"; print $2 > "/tmp/txt_right" }' /tmp/txt

Answer 2

You could try cutting the line, slitting on the underscore
Cat /tmp/txt | cut -d_ -f 1 > txt_left

Answer 3

A sed way:
Shorter and quicker:
sed -ne $'h;s/_.*$//;w /tmp/txt_left\n;g;s/^.*_//;w /tmp/txt_right' /tmp/txt
Explained: It could be written:
sed -ne '
h; # hold (copy current line in hold space)
s/_.*$//; # replace from _ to end of line by nothing
w /tmp/txt_left
# Write current line to file
# (filename have to be terminated by a newline)
g; # get (copy hold space to current line buffer)
s/^.*_//; # replace from begin of line to _ by nothing
w /tmp/txt_right
# write
' /tmp/txt
Bash as bash
This is not a real variable, I use first argument element for doing the job and restore argument list once finish:
set -- "$(</tmp/txt)" "$#"
echo >>/tmp/txt_right ${1#*_}
echo >>/tmp/txt_left ${1%_*}
shift
I unshift the string at first place in argument line,
do operation on $1, than shift the argument line so no variable is used and in fine, the argument line return in his original state
... and this is a pure bash solution ;-)

Answer 4

Using bash process substitution, tee, and cut:
tee -a >(cut -d _ -f 0 > /tmp/txt_left) >(cut -d _ -f 1 >/tmp/txt_right) < /tmp/txt