Bash:InputOutput

echo -n <string>

Print <string> without newline

hexdump -C <file>

Print hexdump of <file> next to the 'normal' representation

Redirecting

command > <file>

Send standard output to new <file> (<file> can be /dev/null if you don't want to see the output)

command >> <file>

Append standard output to <file>

command > <file> 2>&1

Send erroroutput the same file as standard output

cmd 2>&1 > <file> | cmd2

stderr wordt eerst aan stdout gekoppeld (gaat naar pipe) stdout wordt daarna aan file gekoppeld

echo >&2 “error”

redirection can be anywhere in the command, this sends “error” to stderr.

exec > <file>

redirect output current shell to <file> (eg for logging)

exec 3>&-

Close file-descriptor 3

exec 3>&2; exec 2> <file>; exec 2>&3

Save stderr in file-descriptor 3, connect stderr to <file> and restore original stderr

exec 3< <file>

Open file-descriptor 3 to <file>

read -u 3 LINE

Read a line from file-descriptor 3 and store it in variable LINE

exec < <file> 3<&0

Redirect stdin to file and connect file-descriptor 3 to stdin

command << MARKER

input

input

MARKER

stdin reads until MARKER (EOF is often used as marker)