Use bash to write a bash script?

Question

echo "#!/bin/bash\nls -l /home/" > /home/myscript.sh
bash: !/bin/bash\nls: event not found

My script should be:

#!/bin/bash
ls -l /home/

Why does it ignore the echo "" string and think that there is some sort of event? Why does it not recognize #!/bin/bash as a special word?

the same thing happens when I

echo "#!/bin/bash" > /home/myscript.sh

so it's not the new line!

echo -e "#\!/bin/bash" > /home/myscript.sh

writes the file content as:

#\!/bin/bash

Why is this simple action going miserably wrong?

`echo "\n"` does not write a newline, but a backslash and an `n`. Perhaps try `printf` instead. — William Pursell, Aug 04 '22 at 18:48
``` printf "#!/bin/bash" > /home/myscript.sh bash: !/bin/bash: event not found ``` — Ben Muircroft, Aug 04 '22 at 18:49

William Pursell · Answer 1 · 2022-08-04T18:58:09.827

0

From the bash manpage:

Enclosing characters in double quotes preserves the literal value of all characters within the quotes, with the exception of $, `, \, and, when history expansion is enabled, !.

So either use single quotes, or disable history expansion with set +o history.

But don't use echo. Instead, do :

printf '%s\n' '#!/bin/bash' 'ls -l /home/' > /home/myscript

or

cat > /home/myscript << 'EOF'
#!/bin/bash
ls -l /home/
EOF

edited Aug 04 '22 at 18:58

answered Aug 04 '22 at 18:51

William Pursell

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I get ` #!/bin/bash\nls -l /home` as the file contents from this – Ben Muircroft Aug 04 '22 at 18:56

score 0 · Accepted Answer · answered Aug 04 '22 at 18:58

0

echo -e '#!/bin/bash\nls -l /home/' > /home/myscript.sh

a combination of -e and using single quote fixed it.

answered Aug 04 '22 at 18:58

Ben Muircroft

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Use bash to write a bash script?

2 Answers2