How to change the output color without using echo?

Question

Is it possible to change the output color without using echo? Something like "set color to yellow".

I have a script

#!/bin/bash
YELLOW='\033[0;33m'
BLUE='\033[0;34m'
NC='\033[0m' # No Color

echo -e ${YELLOW}
cat file.txt | awk 'NR==1 { print $0; }'
echo -e ${BLUE}
cat file.txt | awk 'NR==2 { print $0; }'
echo -e ${NC}

which prints the first line of file.txt in yellow and the second line in blue. But it also adds extra lines in the places where I have "echo" commands.

I tried something like this:

#!/bin/bash
YELLOW='\033[0;33m'
BLUE='\033[0;34m'
NC='\033[0m' # No Color

${YELLOW} cat file.txt | awk 'NR==1 { print $0; }'
${BLUE} cat file.txt | awk 'NR==2 { print $0; }' ${NC}

But it doesn't work because "echo" command needs -e parameter to display colors.

So my question is: Can I change the output color without using echo? If not, how to remove these extra lines between lines of the file? Is it possible to correct this script to not generate extra lines?

Current output:

 
first line of file.txt

second line of file.txt

Desirable output:

first line of file.txt
second line of file.txt

You can try prinft instead of echo -e

mouviciel
– mouviciel

2018-01-18 15:07:00 +00:00
Commented Jan 18, 2018 at 15:07 — mouviciel
– mouviciel, Commented Jan 18, 2018 at 15:07

iamauser · Accepted Answer · 2018-01-18 15:31:51Z

3

Use printf.

 printf '\e[1;34m%-6s\e[m' "First line of text in BLUE"
 printf '\e[1;31m%-6s\n\e[m' "Second line of text in RED WITH A NEW LINE"

Here is a tiny bash function to do this:

$ cat col.sh
#!/bin/bash

colprint()
{
    printf '\e[1;%dm%-6s\n\e[m' "$1" "$2"
}

# For your input file.
colprint 31 "$(awk 'NR==1{print;}' file.txt)"
colprint 34 "$(awk 'NR==2{print;}' file.txt)"
colprint 33 "$(awk 'NR==3{print;}' file.txt)"

Output in colors of course on a xterm with colors.

edited Jan 18, 2018 at 15:31

answered Jan 18, 2018 at 15:09

iamauser

11.6k6 gold badges40 silver badges57 bronze badges

Sign up to request clarification or add additional context in comments.

Comments

Bach Lien · Accepted Answer · 2018-01-18 15:44:41Z

2

 echo -e -n "$YELLOW"

-n: not add extra newline

answered Jan 18, 2018 at 15:44

Bach Lien

1,0706 silver badges7 bronze badges

2 Comments

iamauser Over a year ago

OP's question asked specifically not to use echo.

maro Over a year ago

It's OK, it also solves the problem with newlines :). I didn't think about modifying the echo command.

that other guy · Accepted Answer · 2018-01-18 22:18:46Z

2

Use tput:

#!/bin/bash

yellow() { tput setaf 3; }
blue() { tput setaf 4; }
nc() { tput sgr0; }

[[ -t 1 ]] || export TERM=dumb

yellow
cat file.txt | awk 'NR==1 { print $0; }'
blue
cat file.txt | awk 'NR==2 { print $0; }'
nc

That way you don't have to hard code terminal codes, and the terminal type and capabilities will be respected. For example, if you're using a terminal that doesn't support colors, you'll get uncolored text instead of garbage.

Here, that same feature is used to get uncolored text when stdout is not a terminal, which is the canonical Unix behavior to avoid problems when piping to other programs.

answered Jan 18, 2018 at 22:18

that other guy

125k12 gold badges187 silver badges214 bronze badges

2 Comments

William Pursell Over a year ago

Sadly, it is becoming less the canonical behavior. I seem to increasingly encounter tools that write terminal color codes to regular files and pipes.

that other guy Over a year ago

TBH, these days I'm pleasantly surprised when a non-native program just manages to set a useful exit code.

Collectives™ on Stack Overflow

How to change the output color without using echo?

3 Answers 3

Comments

2 Comments

2 Comments

Your Answer

Hot Network Questions

Collectives™ on Stack Overflow

3 Answers 3

Comments

2 Comments

2 Comments

Your Answer

Sign up or log in

Post as a guest

Related