# Srm (Unix)
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{{Lowercase title}}
{{more citations needed|date=August 2010}}
{{Infobox software
| name = Secure Remove
| screenshot = Secure remove.png
| screenshot size = 250px
| caption = srm securely erasing a text file.
}}
'''srm''' (or '''Secure Remove''') is a [command line](/source/command_line) utility for [Unix-like](/source/Unix-like) computer systems for secure [file deletion](/source/file_deletion). srm removes each specified file by overwriting, renaming, and truncating it before unlinking. This prevents other people from undeleting or recovering any information about the file from the command line.
==Platform-specific behaviours and bugs==
===Filesystems with hard links===
Attempting to secure delete a file with multiple [hard link](/source/hard_link)s results in a warning from srm stating that the current access path has been unlinked, but the data itself was not overwritten or truncated. This is an undocumented feature of srm 1.2.8 on [Mac OS X 10.9](/source/Mac_OS_X_10.9),-P.[{{cite web|title=srm - securely remove files or directories|accessdate=7 January 2014|author=Matt Gauthier|author-link=Matt Gauthier|location=Man Pages Section 1: Tools|url=http://manned.org/srm|work=srm 1.2.11}}] However, in both the OS X and SourceForge srm implementations, the behaviour of unlinking but not overwriting multi-linked files is always active, as long as the platform reports hard links.[{{cite web|title=sunlink function in srm sunlink.c (SourceForge)|accessdate=7 January 2014|author=doj, null_pointer at SourceForge|url=https://srm.cvs.sourceforge.net/viewvc/srm/srm/src/sunlink.c?revision=1.44|format=C Source|publisher=[SourceForge.net](/source/SourceForge.net)|work=srm 1.2.11, sunlink.c CVS 1.44|date=24 December 2013}}]
srm 1.2.8 on [Mac OS X 10.9](/source/Mac_OS_X_10.9)-n option, which means "overwrite file, but do not rename or unlink it."[{{cite web|title=srm - securely remove files or directories|work=srm 1.2.8, OS X Version 10.9|publisher=[Apple Inc.](/source/Apple_Inc.)|accessdate=7 January 2014|author=doj, null_pointer at [SourceForge](/source/SourceForge)|location=Man Pages Section 1: Tools|url=https://developer.apple.com/library/mac/documentation/Darwin/Reference/ManPages/man1/srm.1.html|date=20 September 2004}}] However, if the file has multiple links, the multiple-link file data protection feature activates first, removing the file, even though the -n option specifies "do not rename or unlink the file".-n option has been removed from the code and manual of srm version 1.2.11, the latest [SourceForge.net](/source/SourceForge.net) version. As a consequence, this option/feature conflict does not occur.[{{cite web|title=srm main.c|accessdate=7 January 2014|author=doj, null_pointer at SourceForge|url=https://srm.cvs.sourceforge.net/viewvc/srm/srm/src/main.c?revision=1.16|format=C Source|publisher=[SourceForge.net](/source/SourceForge.net)|work=srm 1.2.11, main.c CVS 1.16|date=9 June 2011}}]
===OS X===
A number of file systems support [file forks](/source/Fork_(file_system)) (called [resource forks](/source/resource_forks) and named forks on OS X (particularly [HFS+](/source/HFS_Plus)), and alternate data streams on [NTFS](/source/NTFS)), or [extended attributes](/source/extended_attributes). However, OS X is the only platform on which srm securely deletes any of this additional data in files.[{{cite web|title=srm TODO|accessdate=7 January 2014|author=doj, null_pointer at SourceForge|url=https://srm.cvs.sourceforge.net/viewvc/srm/srm/TODO?revision=1.34|format=Plain Text|publisher=[SourceForge.net](/source/SourceForge.net)|work=srm 1.2.11, TODO CVS 1.34|date=24 December 2013}}]
On OS X, only the most common non-data fork, the resource fork, is handled in this way.[{{cite web|title=sunlink function in srm sunlink.c (OS X)|work=Darwin 13.0, OS X Version 10.9: Apple srm 7|publisher=[Apple Inc.](/source/Apple_Inc.)|accessdate=7 January 2014|author=Apple Inc., Matt Gauthier|url=https://opensource.apple.com/source/srm/srm-7/srm/src/sunlink.c|format=C Source}}] This support was included in Apple’s {{mono|srm}} 1.2.8{{hsp}}[{{cite web|title=Apple - Open Source|work=Darwin 13.0, OS X Version 10.9|publisher=[Apple Inc.](/source/Apple_Inc.)|accessdate=7 January 2014|author=Apple Inc.|url=https://www.apple.com/opensource/}}][{{cite web|title=srm README.OsX (sic)|accessdate=7 January 2014|author=doj, null_pointer at SourceForge|url=https://srm.cvs.sourceforge.net/viewvc/srm/srm/README.OsX?revision=1.2|format=Plain Text|publisher=[SourceForge.net](/source/SourceForge.net)|work=srm 1.2.11, README.OsX (sic) CVS 1.2|date=22 November 2010}}] and SourceForge's {{mono|srm}} 1.2.9.[{{cite web|title=srm ChangeLog 2008-07-08|accessdate=7 January 2014|author=doj, null_pointer at SourceForge|url=https://srm.cvs.sourceforge.net/viewvc/srm/srm/ChangeLog?revision=1.4|format=Plain Text|publisher=[SourceForge.net](/source/SourceForge.net)|work=srm 1.2.11, ChangeLog CVS 1.4|date=25 November 2010}}]
srm was removed from OS X/macOS in v10.11 El Capitan, as part of the removal of the "Secure Empty Trash" feature for security reasons.[{{cite web|title=macbook pro - macOS High Sierra: Where is the Secure Empty Trash option? - Ask Different|accessdate=28 March 2021|url=https://apple.stackexchange.com/q/327239}}]
===OpenBSD===
In srm 1.2.11, released on 25 November 2010,[{{cite web|title=secure rm - Browse files at SourceForge.net|accessdate=7 January 2014|author=doj, null_pointer at SourceForge|url=http://manned.org/srm|publisher=[SourceForge.net](/source/SourceForge.net)}}] the [OpenBSD](/source/OpenBSD) rm-compatible option, -P, is documented have an overwriting pattern matching OpenBSD's rm.-x option, which restricts srm to one [file system](/source/file_system), is not supported.