在Shell脚本中使用echo丢失字符

Question

I tried to write a shell script that runs commands using a specific like sudo su - user so I used sudo -H -u user bash -c and all is working well except some echo commands.

This is not working and I can't solve it

sudo -H -u mailq bash -c "cd /var/www/html; echo -e \"
#!/bin/bash

NAME=\"user\"
DIR=/var/www/html    
cd \$DIR
\" > start"

it prints like

#!/bin/bash


NAME=user
DIR=/var/www/html    
cd 

Answer 1

Compare your original implementation to the following:

sudo -H -u mailq sh -c 'cat >"$1"' _ /var/www/html/start <<'EOF'
#!/bin/bash
NAME=user
DIR=/var/www/html
cd "$DIR"
EOF

Because <<'EOF' has the heredoc quoted, all contents within are literal. There's no need to escape \\$DIR to prevent it from being immediately evaluated.

Answer 2

Not entirely clear what OP is asking, but there seems to be an issue with double and single quotes in the bash -c arguments.

$ sudo -H -u mailq bash -c "cd /var/www/html; echo ' 
#!/bin/bash

NAME=\"user\"
DIR=\"/var/www/html\"    
cd \$DIR
'>~/start"

Output will be written to ~/start .

$ cat ~/start 

#!/bin/bash

NAME="user"
DIR="/var/www/html"    
cd $DIR

Note, as @Charles_Duffy points out, this kinda script insertion/execution can be hazardous and difficult to debug.