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Full Discussion: Dangerous rm -rf command
The Lounge War Stories Dangerous rm -rf command Post 302948321 by Don Cragun on Sunday 28th of June 2015 08:58:08 PM
Old 06-28-2015
Quote:
Originally Posted by Riker1204
Code:
var="/some/place"
rm -rf "${vra}/"*

Does the rm command throw an error when ${vra} does not exist or does it simply proceed with a null byte or something followed by /* erasing everything in its path.

As a beginner in Linux / Bash everything seems to bring up a question.
This has been answered many times before. If the variable vra has not been defined, the command:
Code:
rm -rf "${vra}/"*

will invoke rm with one operand for every file in your system's root directory that does not start with a period. The rm command will then attempt to remove every file in the file hierarchies rooted in those pathnames and print a diagnostic message for every file it is unable to remove until you kill that command or wipe out your system.

UNIX and Linux system utilities are generally very happy to try to do whatever you tell them to even if you have told them to do something that could be disastrous. They don't generally try to second guess you and tell you you might be making a mistake.
 

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IRSEND(1)							   User Commands							 IRSEND(1)

NAME
irsend - basic LIRC program to send infra-red commands SYNOPSIS
irsend [options] DIRECTIVE REMOTE CODE [CODE...] DESCRIPTION
Asks the lircd daemon to send one or more CIR (Consumer Infra-Red) commands. This is intended for remote control of electronic devices such as TV boxes, HiFi sets, etc. DIRECTIVE can be: SEND_ONCE - send CODE [CODE ...] once SEND_START - start repeating CODE SEND_STOP - stop repeating CODE LIST - list configured remote items SET_TRANSMITTERS - set transmitters NUM [NUM ...] SIMULATE - simulate IR event REMOTE is the name of a remote, as described in the lircd configuration file. CODE is the name of a remote control key of REMOTE, as it appears in the lircd configuration file. NUM is the transmitter number of the hardware device. For the LIST DIRECTIVE, REMOTE and/or CODE can be empty: LIST "" "" - list all configured remote names LIST REMOTE "" - list all codes of REMOTE LIST REMOTE CODE - list only CODE of REMOTE The SIMULATE command only works if it has been explicitly enabled in lircd. -h --help display usage summary -v --version display version -d --device use given lircd socket [/var/run/lirc/lircd] -a --address=host[:port] connect to lircd at this address -# --count=n send command n times EXAMPLES
irsend LIST DenonTuner "" irsend SEND_ONCE DenonTuner PROG-SCAN irsend SEND_ONCE OnkyoAmpli VOL-UP VOL-UP VOL-UP VOL-UP irsend SEND_START OnkyoAmpli VOL-DOWN ; sleep 3 irsend SEND_STOP OnkyoAmpli VOL-DOWN irsend SET_TRANSMITTERS 1 irsend SET_TRANSMITTERS 1 3 4 irsend SIMULATE "0000000000000476 00 OK TECHNISAT_ST3004S" FILES
/etc/lirc/lircd.conf Default lircd configuration file. It should contain all the remotes, their infra-red codes and the corresponding timing and wave- form details. DIAGNOSTICS
If lircd is not running (or /var/run/lirc/lircd lacks write permissions) irsend aborts with the following diagnostics: "irsend: could not connect to socket" "irsend: Connection refused" (or "Permission denied"). SEE ALSO
The documentation for lirc is maintained as html pages. They are located under html/ in the documentation directory. lircd(8), mode2(1), smode2(1), xmode2(1), irrecord(1), irw(1), http://www.lirc.org. irsend 0.9.0-pre1 October 2010 IRSEND(1)
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