kdb provides the following system commands:

System Commands:

\Exit q session
 Toggle q/k language or exit debug mode
_Compile q script (hide source)
*Execute OS command
1Redirect standard out to file
2Redirect standard error to file
aList tables in namespace. No parameter means current NS
bList dependencies in NS. No parameter means current NS
BInvalid dependencies in NS. No parameter means current NS
cReturn/set console height & width -c H W 23 79
CReturn/set web browser display height & width -C H W 36 2000
dReturn/set current namespace `.
eReturn/set error trap mode -e [0|1] 0
fList functions in NS. No parameter means current NS
lLoad q script or database directory
oReturn/set local time offset in hours from GMT -o N 0N
pReturn/set port used \p portNumber . Note 0=no listening socket.
PReturn/set print precision. 0 = maximum -P N 7
rDisplay replication (host;port); OR oldfile newfile /- Rename a file
sDisplay number of slaves used for parallel execution -s N 0
SDisplay/set seed for pseudo-random number generator -S N -314159
tDisplay/set timer in milliseconds. 0=timer off -t N 0
tstime and space measuring of function call
TDisplay/set timeout (secs) for single client call. 0=off -T N 0
uReload user:password file -u F
vDisplay list of variables in current namespace
wWorkspace memory (used/heap/peak/max/mapped); OR 0 /- print internalised symbol count and memory usage
WDisplay/set weekday offset. 0 = Saturday -W N 2
x.z.?? Reset .z function
zDisplay/set date conversion format from string -z [0|1] 0