Split utils some more, add printing utils

Author: cirosantilli

README.md

@@ -23,18 +23,41 @@ Includes Linux concepts and utilities that work on Linux, not necessarily in the
     1. [System Call](system-call/)
     1. [sysctl](sysctl.md)
     1. [Special files](special-files.md)
-        1. [proc filesystem](proc-filesystem.md)
-        1. [dev filesystem](dev-filesystem.md)
+        1.  [proc filesystem](proc-filesystem.md)
+        1.  [dev filesystem](dev-filesystem.md)
+            1. [mknod](mknod.md)
 1.  Initialization
     1. [Install OS](install-os.md): how to install a new OS
     1. [Boot](boot.md)
     1. [Init](init.md): System V, Upstart
-1.  Base topics
-    1. [Filesystem](filesystem.md) POSIX file permissions.
-        1. [Hardlink](hardlink.md)
-    1. [File permissions](file-permissions.md): filesystem, hard disks, mounting, partitions
-    1. [Terminal](terminal.md): terminal emulators, ANSI escapes, control characters
-        1. [Guake](guake.sh)
+1.  System information
+    1.  [lsb_release](lsb_release.md)
+    1.  [uname](uname.md)
+    1.  Hardware
+        [lspci](lspci.md)
+1.  [Filesystem](filesystem.md)
+    1.  [File permissions](file-permissions.md)
+    1.  [Hardlink](hardlink.md)
+    1.  [badblocks](badblocks.md)
+    1.  [blkid](blkid.md)
+    1.  [chown](chown.sh)
+    1.  [chmod](chmod.sh)
+    1.  [du](du.md)
+    1.  ext filesystems
+        1. [e2label](e2label.md)
+        1. [e2fsck](e2fsck.md)
+        1. [e2fsprogs](e2progs.md)
+        1. [mke2fs](mke2fs.md)
+    1.  [fdisk](fdisk.md)
+    1.  [fuser](fuser.md)
+    1.  [lsblk](lsblk.md)
+    1.  [mktemp](mktemp.md)
+    1.  [pathchk](pathchk.md)
+    1.  [ramfs](ramfs.md)
+    1.  [swap partition](swap-partition.md)
+    1.  [UUID](uuid.md)
+1. [Terminal](terminal.md): terminal emulators, ANSI escapes, control characters
+    1. [Guake](guake.sh)
 1.  Stream and file manipulation
     1. [cat](cat.md)
     1. [head](head.md)
@@ -86,14 +109,6 @@ Includes Linux concepts and utilities that work on Linux, not necessarily in the
 1.  File managers
     1. [Krusader](krusader.md)
     1. [vifm](vifm.md)
-1.  Partitions, filesystems
-    1. [badblocks](badblocks.md)
-    1. [blkid](blkid.md)
-    1. [du](du.md)
-    1. [e2fsck](e2fsck.md)
-    1. [e2fsprogs](e2progs.md)
-    1. [lsblk](lsblk.md)
-    1. [swap partition](swap-partition.md)
 1.  [Compilation and libraries](compile.md)
     1. [GDB](gdb.md)
     1. [Library](library.md)
@@ -172,25 +187,30 @@ Includes Linux concepts and utilities that work on Linux, not necessarily in the
     1. [RST](rst/)
 1.  [Virtual machine](virtual-machine/)
     1. [Docker](docker/)
+    1. [User mode Linux](user-mode-linux.md)
     1. [Vagrant](vagrang/)
 1.  [Configuration automation](config-automation.md)
     1. [chef](chef/)
     1. [puppet](puppet.md)
-1.  Hardware
-    [lspci](lspci.md)
+1.  Printing
+    1. [CUPS](cups.md)
+        1. [lp](lp.md)
+        1. [lpstat](lpstat.md)
+        1. [lpoptions](lpoptions.md)
+        1. [system-config-printer](system-config-printer.md)
 1.  Misc
+    1. [cron](cron.sh)
     1. [logrotate](logrotate.md)
     1. [factor](factor.md)
     1. [xargs](xargs.md)
 1.  [Bibliography](bibliography.md)
 
 ## WIP
 
+1.  Filesystem
+    [eCryptfs](ecryptfs.md)
 1.  [Hardware](hardware.md)
     1.  [lshw](lshw.md)
-    1.  Printer
-        1. [system-config-printer](system-config-printer.md)
-        1. CUPS
 1.  [gcov](gcov.md)
 1.  Misc
     1. [sys-filesystem](sys-filesystem.md)

Re

@@ -0,0 +1,13 @@
+# arch
+
+Coreutils.
+
+Same as `uname -m`:
+
+    arch
+
+Sample outputs:
+
+    x86_64
+
+So basically an alias.

arch.md

@@ -0,0 +1,100 @@
+## chmod
+
+  # POSIX
+
+  # Change file permissions
+
+  # Syntax:
+
+    # chomod [ugoa][+-=][rwxXst]+
+
+  # Make f executable for all (owner, group and other);
+
+    chmod a+x "$f"
+
+  # Makes f readable for all:
+
+    chmod a+r "$f"
+
+  # The difference between using `a` and nothing is that when using
+  # nothing `umask` comes into play.
+
+    umask 002
+    chmod +w "$f"
+    stat -c "%a" "$f"
+      #220
+    chmod a=w "$f"
+    stat -c "%a" "$f"
+      #222
+    chmod o=w "$f"
+    stat -c "%a" "$f"
+      #002
+
+  # Make f not executable for all:
+
+    chmod -x "$f"
+
+  # Make file not executable and not writeble by all:
+
+    chmod =r "$f"
+
+  # Make f executable for owner:
+
+    chmod u+x "$f"
+
+  # Makes f executable for group and other:
+
+    chmod go+x "$f"
+
+  # Makes f readable and writible for all:
+
+    chmod +rw "$f"
+
+  # Same as `chmod =rwx`:
+
+    chmod 777 "$f"
+
+  ## sticky bit, suid sgid bits
+
+    # Sticky bit:
+
+      chmod 1000 "$f"
+      chmod o=t "$f"
+      chmod a=t "$f"
+      stat -c "%A" "$f"
+        #---------T
+      chmod a-t "$f"
+      chmod u=t "$f"
+      chmod g=t "$f"
+      stat -c "%A" "$f"
+        #---------T
+      chmod =s "$f"
+      chmod 6000
+        #set suid and sgid
+      chmod u=s "$f"
+      chmod 4000
+        #set suid and sgid
+      chmod g=s "$f"
+      chmod 2000
+
+    # Can't clear them on numeric mode, only symbolic:
+
+      chmod 7777 f
+      stat -c "%A" "$f"
+        #-rwsrwsrws
+      chmod 0 f
+      stat -c "%A" "$f"
+        #---S--S--T
+      chmod a-st f
+      stat -c "%A" "$f"
+        #----------
+
+  # Can only change permissions for files you own
+  # even if you do not have all the permissions on the file:
+
+    su a
+    touch a
+    chmod 777 a
+    su b
+    if ! chmod 770 a; then assert true; fi
+

chmod.sh

@@ -0,0 +1,39 @@
+## chown
+
+  # POSIX 7
+
+  # Change owner and group of files.
+
+  # You must use sudo to do this, because otherwise users would be able to:
+
+  # - steal ownership of files
+  # - git ownership to users who do not want to own the files
+
+    su a
+    mkdir d
+    touch d/f
+    sudo chown newuser:newgroup d
+      #must use sudo to chown
+    [ `stat -c '%U' d` = newuser ] || exit 1
+    [ `stat -c '%G' d` = newgroup ] || exit 1
+    [ `stat -c '%U' d/f` = a ] || exit 1
+
+  # `-R` for recursive operation:
+
+    su a
+    mkdir d
+    touch d/f
+    sudo chown b d
+    [ `stat -c '%U' d` = newuser ] || exit 1
+    [ `stat -c '%G' d` = newgroup ] || exit 1
+    [ `stat -c '%U' d/f` = newuser ] || exit 1
+    [ `stat -c '%G' d/f` = newgroup ] || exit 1
+
+  # To change only user:
+
+    sudo chown newuser
+
+  # To change only group:
+
+    sudo chown :newgroup
+

chown.sh

@@ -0,0 +1,131 @@
+## cron
+
+  # Tell the computer to do things at specified times automatially.
+
+  ## crontab
+
+    # POSIX 7.
+
+    # Utility to manage crobjobs.
+
+    # It is basically a frontend for the `/etc/crontab` file which an be edited directly.
+
+    # It is not possible launch graphical applications via cron!
+
+    # Edit user cron jobs in vim
+
+      crontab -e
+
+    # Sample line:
+
+      1 2 3 4 5 /path/to/cmd.sh arg1 arg2 >/dev/null 2>&1
+
+    # Fields:
+
+    # - 1: Minute (0-59)
+    # - 2: Hours (0-23)
+    # - 3: Day (0-31)
+    # - 4: Month (0-12 [12 == December])
+    # - 5: Day of the week(0-7 [7 or 0 == sunday])
+    # - /path/to/command - Script or command name to schedule#
+
+    # Special notations:
+
+    # - * : every
+    # - */5 : every five
+    # - 1,3,6 : several
+    # - 1-5 : ranges
+
+    # Convenient altenatives to the fields:
+
+    # - @reboot	Run once, at startup.
+    # - @yearly	Run once a year, "0 0 1 1 *".
+    # - @annually	(same as @yearly)
+    # - @monthly	Run once a month, "0 0 1 * *".
+    # - @weekly	Run once a week, "0 0 * * 0".
+    # - @daily	Run once a day, "0 0 * * *".
+    # - @midnight	(same as @daily)
+    # - @hourly	Run once an hour, "0 * * * *".
+
+    # Example:
+
+      @daily /path/to/cmd.sh arg1 arg2 >/dev/null 2>&1
+
+    # `>/dev/null 2>&1` prevents cron from sending notification emails.
+
+    # Otherwise if you want them add:
+
+      #MAILTO="[email protected]"
+
+    # to the config file.
+
+    # List all cronjobs:
+
+      crontab -l
+
+    # List all cronjobs for a given user:
+
+      crontab -u user -l
+
+    # Erase all cronjobs:
+
+      crontab -r
+
+    # Erase all cronjobs for a given user only
+
+      crontab -r -u username
+
+  ## batch
+
+    # POSIX 7
+
+    # Superset of `at`.
+
+    # Execute only when system load average goes below 1.5,
+    # starting from now!
+
+      cd "`mktemp -d`"
+      echo "touch a" | batch
+
+    # Same, but with at you can change to any time:
+
+      echo "touch a" | at -q b now
+
+  ## at
+
+    # Schedule job at a single specified time.
+
+    # Not for a periodic jobs.
+
+      cd "`mktemp -d`"
+      echo "touch a" | at now + 1 minutes
+        #in one minute `test -f a`
+      echo "echo a" | at now + 1 minutes
+        #nothing happens!
+        #of course, job does not run in current shell
+      echo "xeyes" | at now + 1 minutes
+        #nothing happens
+
+    # List jobs:
+
+      atq
+
+    # Remove job with id 1:
+
+      atrm 1
+
+    # Id can be found on atq output.
+
+    #inner workings
+
+      echo "touch a" | at now + 10 minutes
+      d=/var/spool/cron/atjobs
+      sudo cat "$d/$(sudo ls "$d" | head -n 1)"
+        #note how the entire environment
+        #and current dir are saved and restored
+
+      sudo cat /usr/lib/cron/at.allow
+        #if exists, only listed users can `at`
+      sudo cat /usr/lib/cron/at.deny
+        #if allow exists, this is ignored!
+        #if not, denies only to listed users