Quick reference guide Linux

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4. Processes

& S
If a command is terminated by & the shell executes it in the background.  
CTRL-C S
Send the running process a TERM signal that usually terminates the process.  
CTRL-Z S
Send the running process a TSTP signal that usually suspends the process.  
at, atq, atrm U
Queue, examine or delete jobs for later execution. To use this facility consult both the man pages and your system administrator.  
bg [job[s]] S
Put suspended jobs[s] or the current suspended job in the background.
The syntax for the job[s] argument is %number
 
crontab[-elr] U
Edit (-e), list (-l), or remove (-r) crontab files. To use this facility for the first time contact your sysadmin. The format of the file for running commands at regular intervals is
minute hour day month day_of_week command
(0-59, *) (0-23, *) (1-31, *) (1-12, *) (0-6, *)
 
fg [job[s]] S
Bring specified job[s] or the current job to the foreground.  
jobs [job[s]] S
Display the status of specified or all running and suspended jobs.  
kill [signal] process_ID[s] US
kill [-s signame] process_ID[s]  
Terminate or signal a process. Send signal or signame to process_ID[s]. By default the TERM signal (15) is sent that usually terminates the process. With kill -l all valid signal names signame can be listed.  
nohup program [arguments] U
Run a command immune to hangups, i.e continues to run after logging out. STDOUT is redirected to nohup.out or /nohup.out  
nice [-value] program (not csh and tcsh) U
nice [+value] program (csh and tcsh only) S
Run program with modified scheduling priority. Without value the priority is decreased by 10, allowed values are 1 to 19.  
pp [string] A
Report process status of processes that match string (regular expression).  
ps [-efl] [pid[s]] U
Report process status. For a list of all processes use pp without arguments instead.  
renice priority [-g gid[s]] [-p pid[s]] [-u user[s]] U
Alter priority of running processes. Users can set priority from 0 (normal) to 19 (very nice). Processes are selected by gid pid uid or user name.  
sched [+]hh:mm command[s] (tcsh and zsh only) S
sched [-item] (tcsh and zsh only)  
Execute command[s] at hh:mm or after +hh:mm hours. With no arguments, prints the list of scheduled commands. With the argument -item, removes the given item from the list.  
time command S
Time a command. CPU times and the real elapsed time are reported.  
top P
Display top CPU processes. Not recommended, as it puts additional load to a machine. For a quick overview of the system load use uptime instead.  
uptime U
Prints current time, how long the system has been running and the average load within the last 1, 5 and 15 minutes.  

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