Bash:InputOutput
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- 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)