CRONTAB(1)\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0 General Commands Manual\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0 CRONTAB(1)<\/p>\n
NAME
\ncrontab – maintain crontab files for individual users (Vixie Cron)<\/p>\n
SYNOPSIS
\ncrontab [ -u user ] file
\ncrontab [ -u user ] [ -i ] { -e | -l | -r }<\/p>\n
DESCRIPTION
\ncrontab\u00a0 is\u00a0 the\u00a0 program used to install, deinstall or list the tables
\nused to drive the cron(8) daemon in Vixie Cron.\u00a0\u00a0 Each\u00a0 user\u00a0 can\u00a0 have
\ntheir\u00a0\u00a0\u00a0 own\u00a0\u00a0\u00a0 crontab,\u00a0\u00a0\u00a0 and\u00a0\u00a0\u00a0 though\u00a0\u00a0\u00a0 these\u00a0\u00a0\u00a0 are\u00a0\u00a0\u00a0 files\u00a0\u00a0 in
\n\/var\/spool\/cron\/crontabs, they are not intended to be edited directly.<\/p>\n
If the \/etc\/cron.allow file exists, then you must be listed\u00a0 (one\u00a0 user
\nper\u00a0 line)\u00a0 therein in order to be allowed to use this command.\u00a0 If the
\n\/etc\/cron.allow file does not exist but the\u00a0 \/etc\/cron.deny\u00a0 file\u00a0 does
\nexist,\u00a0 then you must not be listed in the \/etc\/cron.deny file in order
\nto use this command.<\/p>\n
If neither of these files exists, then depending on site-dependent con\u2010
\nfiguration\u00a0 parameters, only the super user will be allowed to use this
\ncommand, or all users will be able to use this command.<\/p>\n
If both files exist then \/etc\/cron.allow takes precedence. Which\u00a0 means
\nthat\u00a0 \/etc\/cron.deny\u00a0 is not considered and your user must be listed in
\n\/etc\/cron.allow in order to be able to use the crontab.<\/p>\n
Regardless of the existance of any of these files, the root administra\u2010
\ntive\u00a0 user\u00a0 is\u00a0 always allowed to setup a crontab.\u00a0 For standard Debian
\nsystems, all users may use this command.<\/p>\n
If the -u option is given, it specifies the\u00a0 name\u00a0 of\u00a0 the\u00a0 user\u00a0 whose
\ncrontab\u00a0 is\u00a0 to\u00a0 be\u00a0 used (when listing) or modified (when editing). If
\nthis option is not given, crontab examines “your”\u00a0 crontab,\u00a0 i.e.,\u00a0 the
\ncrontab\u00a0 of the person executing the command.\u00a0 Note that su(8) can con\u2010
\nfuse crontab and that if you are running inside\u00a0 of\u00a0 su(8)\u00a0 you\u00a0 should
\nalways use the -u option for safety’s sake.<\/p>\n
The\u00a0 first\u00a0 form\u00a0 of this command is used to install a new crontab from
\nsome named file or standard\u00a0 input\u00a0 if\u00a0 the\u00a0 pseudo-filename\u00a0 “-”\u00a0 is
\ngiven.<\/p>\n
The\u00a0 -l\u00a0 option\u00a0 causes the current crontab to be displayed on standard
\noutput. See the note under DEBIAN SPECIFIC below.<\/p>\n
The -r option causes the current crontab to be removed.<\/p>\n
The -e option is used to edit the\u00a0 current\u00a0 crontab\u00a0 using\u00a0 the\u00a0 editor
\nspecified\u00a0 by\u00a0 the\u00a0 VISUAL\u00a0 or EDITOR environment variables.\u00a0 After you
\nexit from the editor, the modified crontab will be installed\u00a0 automati\u2010
\ncally.\u00a0 If\u00a0 neither\u00a0 of\u00a0 the environment variables is defined, then the
\ndefault editor \/usr\/bin\/editor is used.<\/p>\n
The -i option modifies the -r option to prompt the\u00a0 user\u00a0 for\u00a0 a\u00a0 ‘y\/Y’
\nresponse before actually removing the crontab.<\/p>\n
DEBIAN SPECIFIC
\nThe\u00a0 “out-of-the-box”\u00a0 behaviour for crontab -l is to display the three
\nline “DO NOT EDIT THIS FILE” header that is placed at the beginning\u00a0 of
\nthe\u00a0 crontab\u00a0 when\u00a0 it\u00a0 is\u00a0 installed. The problem is that it makes the
\nsequence<\/p>\n
crontab -l | crontab –<\/p>\n
non-idempotent — you keep adding copies of\u00a0 the\u00a0 header.\u00a0 This\u00a0 causes
\npain\u00a0 to scripts that use sed to edit a crontab. Therefore, the default
\nbehaviour of the -l option has been changed to not output such\u00a0 header.
\nYou\u00a0 may obtain the original behaviour by setting the environment vari\u2010
\nable CRONTAB_NOHEADER to ‘N’, which will cause the crontab\u00a0 -l\u00a0 command
\nto emit the extraneous header.<\/p>\n
SEE ALSO
\ncrontab(5), cron(8)<\/p>\n
FILES
\n\/etc\/cron.allow
\n\/etc\/cron.deny
\n\/var\/spool\/cron\/crontabs<\/p>\n
There\u00a0\u00a0\u00a0 is\u00a0\u00a0\u00a0 one\u00a0\u00a0 file\u00a0\u00a0 for\u00a0\u00a0 each\u00a0\u00a0 user’s\u00a0\u00a0 crontab\u00a0\u00a0 under\u00a0\u00a0 the
\n\/var\/spool\/cron\/crontabs directory. Users are not allowed to\u00a0 edit\u00a0 the
\nfiles\u00a0 under\u00a0 that directory directly to ensure that only users allowed
\nby the system to run periodic tasks can add them,\u00a0 and\u00a0 only\u00a0 syntacti\u2010
\ncally correct crontabs will be written there.\u00a0 This is enforced by hav\u2010
\ning the directory writable only by the crontab\u00a0 group\u00a0 and\u00a0 configuring
\ncrontab command with the setgid bid set for that specific group.<\/p>\n
STANDARDS
\nThe\u00a0 crontab command conforms to IEEE Std1003.2-1992 (“POSIX”).\u00a0 This
\nnew command syntax differs from previous versions\u00a0 of\u00a0 Vixie\u00a0 Cron,\u00a0 as
\nwell as from the classic SVR3 syntax.<\/p>\n
DIAGNOSTICS
\nA\u00a0 fairly\u00a0 informative\u00a0 usage\u00a0 message appears if you run it with a bad
\ncommand line.<\/p>\n
cron requires that each entry in a crontab end in a newline\u00a0 character.
\nIf\u00a0 the\u00a0 last entry in a crontab is missing the newline, cron will con\u2010
\nsider the crontab (at least partially) broken and refuse to install it.<\/p>\n
AUTHOR
\nPaul Vixie <paul@vix.com> is the author of cron and original creator of
\nthis\u00a0 manual page. This page has also been modified for Debian by Steve
\nGreenland, Javier Fernandez-Sanguino and Christian Kastner.<\/p>\n
4th Berkeley Distribution\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0 19 April 2010\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0 CRONTAB(1)
\nManual page crontab(1) line 58\/108 (END) (press h for help or q to quit)<\/p>\n","protected":false},"excerpt":{"rendered":"
CRONTAB(1)\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0 General Commands Manual\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0 CRONTAB(1) NAME crontab – maintain crontab files for individual users (Vixie Cron) SYNOPSIS crontab [ -u user ] file crontab [ -u user ] [ -i ] { -e | -l | -r } DESCRIPTION crontab\u00a0 is\u00a0 the\u00a0 program used to install, deinstall or list the tables used to drive the […]<\/p>\n","protected":false},"author":1,"featured_media":0,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"_sitemap_exclude":false,"_sitemap_priority":"","_sitemap_frequency":"","footnotes":""},"categories":[8],"tags":[],"class_list":["post-304","post","type-post","status-publish","format-standard","hentry","category-shell"],"_links":{"self":[{"href":"https:\/\/www.linuxboxen.dk\/index.php?rest_route=\/wp\/v2\/posts\/304","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/www.linuxboxen.dk\/index.php?rest_route=\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/www.linuxboxen.dk\/index.php?rest_route=\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/www.linuxboxen.dk\/index.php?rest_route=\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"https:\/\/www.linuxboxen.dk\/index.php?rest_route=%2Fwp%2Fv2%2Fcomments&post=304"}],"version-history":[{"count":0,"href":"https:\/\/www.linuxboxen.dk\/index.php?rest_route=\/wp\/v2\/posts\/304\/revisions"}],"wp:attachment":[{"href":"https:\/\/www.linuxboxen.dk\/index.php?rest_route=%2Fwp%2Fv2%2Fmedia&parent=304"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/www.linuxboxen.dk\/index.php?rest_route=%2Fwp%2Fv2%2Fcategories&post=304"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/www.linuxboxen.dk\/index.php?rest_route=%2Fwp%2Fv2%2Ftags&post=304"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}