At Bowdoin there are two public remote hosts running Linux: dover and foxtrot. They are public and accessible to everyone. Use them as you like, but be careful not to run intensive processes because that will slow down the machine and disturb anyone else who might be using it.
Example:
ssh doverBy default, without user name, this assumes the same user name as on the current machine. To specify a different user name use:
ssh ltoma©doveror
ssh -l ltoma doverIf you are on the Bowdoin network, it is sufficient to specify the name of the host. If you were outside campus, you would use dover.bowdoin.edu instead of dover:
To exit the session:
logoutor
exit
man [command-name]: get description of commandman -k [keyword] : list commands containing keyword
pwd: stands for 'print working directory'.
Prints current directory name (path).
cd [pathname]: stands for 'change directory'.
Change the current directory to the one specified.
Note: pathname can be relative or absolute.
cd ..: go to parent directory
ls: stands for 'list'. List files in current directory.To see arguments, type:
man lsSome useful arguments:
ls -a: list all. You will see hidden files. ls -l: list long format. You will see all attributes of files. ls -lh: print sizes nicely using K, M, G
mkdir [pathname]: stands for 'make directory'. Creates a new directory.
rm [pathname]: remove the file specified by [pathname]Try using it to remove a whole directory. You'll see that it does not work. Now try this:
rm -R /var/tmp/outThis removes recursively the directory, that is it removes the directory and everything inside it.
rmdir [pathname]: stands for 'remove directory'.
Removes the specified directory.
If the directory is not empty, you'll need to use argument '-R'.
cat [filename]: print out contents of file on screen.
cat [file1] [file2] : concatenate [file1] and [file2] (their contents)
and print the result on the screen.
mv [old] [new] : old and new are pathnames.
Move one to the other.
Note: can move files or whole directories.
cp [old] [new]: old and new are pathnames.
Copy the file from the old pathname to the new one.
The file is copied and thus the original [old] still exists.
To copy directories with cp, need to use argument '-R' which stands for 'recursive':
cp -R /var/tmp/misc /var/tmp/out: this copies folder misc to folder out.
more [pathname]: one page at a time. spacebar scrolls. q quits.
less [pathname] : like more, but can also move backwards with 'p'.
chmod: change permission of a fileSuch as:
chmod +x [filename]: this gives execute permission to everyone chmod go-r [filename]: this takes away 'read' permission from group and otherExample:
ls -rw-rw-rw-@ 1 ltoma staff 23617 Nov 30 2012 model-layers.pdf -rw-rw-rw-@ 1 ltoma staff 7276 Jul 2 2013 paper.aux -rw-rw-rw-@ 1 ltoma staff 2771 Jul 1 2013 paper.bbl -rw-rw-rw-@ 1 ltoma staff 883 Jul 1 2013 paper.blg -rw-rw-rw-@ 1 ltoma staff 22084 Jul 2 2013 paper.log -rw-rw-rw-@ 1 ltoma staff 2401983 Jul 2 2013 paper.pdf -rw-rw-rw- 1 ltoma staff 235898 Jul 2 2013 paper.synctex.gz -rw-rw-rw-@ 1 ltoma staff 86334 Jul 2 2013 paper.tex drwxrwxrwx@ 21 ltoma staff 714 May 14 2013 plots -rw-rw-rw-@ 1 ltoma staff 643927 Apr 24 2013 region.pdf -rw-rw-rw-@ 1 ltoma staff 59744 May 23 2012 sig-alternate.cls -rw-rw-rw-@ 1 ltoma staff 5736 Jul 1 2013 vis.bib Lauras-MacBook-Pro:viewshedLI-paper ltoma$ Lauras-MacBook-Pro:viewshedLI-paper ltoma$ chmod go-r vis.bib Lauras-MacBook-Pro:viewshedLI-paper ltoma$ ls -l vis.bib -rw--w--w-@ 1 ltoma staff 5736 Jul 1 2013 vis.bib Lauras-MacBook-Pro:viewshedLI-paper ltoma$
head [filename]: display the first few lines of [filename]
tail [filename]: display the last few lines of [filename]
grep [pattern] [filename]: search for [pattern] in [filename].
wc [filename]: word count use -l to count lines use -w to count words
date: show current date and time
who: show users who are logged in on the machine
w: show users and what they are doing
df: display free disk space. Easier to read if used with option '-h'.Example:
Lauras-MacBook-Pro:viewshedLI-paper ltoma$ df Filesystem 512-blocks Used Available Capacity iused ifree %iused Mounted on /dev/disk0s2 975425848 532155360 442758488 55% 66583418 55344811 55% / devfs 365 365 0 100% 634 0 100% /dev map -hosts 0 0 0 100% 0 0 100% /net map auto_home 0 0 0 100% 0 0 100% /home Lauras-MacBook-Pro:viewshedLI-paper ltoma$ df -h Filesystem Size Used Avail Capacity iused ifree %iused Mounted on /dev/disk0s2 465Gi 254Gi 211Gi 55% 66583418 55344811 55% / devfs 183Ki 183Ki 0Bi 100% 634 0 100% /dev map -hosts 0Bi 0Bi 0Bi 100% 0 0 100% /net map auto_home 0Bi 0Bi 0Bi 100% 0 0 100% /home Lauras-MacBook-Pro:viewshedLI-paper ltoma$
top: display system tasks (processes).Example:
Processes: 197 total, 2 running, 3 stuck, 192 sleeping, 900 threads 00:40:27 Load Avg: 1.12, 0.93, 0.85 CPU usage: 3.24% user, 1.85% sys, 94.89% idle SharedLibs: 1256K resident, 0B data, 0B linkedit. MemRegions: 40266 total, 2181M resident, 77M private, 1513M shared. PhysMem: 6909M used (1524M wired), 8747M unused. VM: 502G vsize, 1026M framework vsize, 2249975(0) swapins, 2430156(0) swapouts. Networks: packets: 3300025/3511M in, 2946854/966M out. Disks: 766443/42G read, 762492/29G written. PID COMMAND %CPU TIME #TH #WQ #PORT #MREG MEM RPRVT PURG CMPR VPRVT VSIZE PGRP PPID STATE UID FAULTS COW MSGSENT MSGRECV 4957 top 6.9 00:00.67 1/1 0 22 36 2360K 2132K 0B 0B 36M 2395M 4957 4631 running 0 13875+ 76 841665+ 420817+ 4955 mdworker 0.0 00:00.10 3 0 56 70 2864K 1900K 0B 0B 100M 2462M 4955 151 sleeping 501 2927 217 933 364 4950 mdworker 0.0 00:00.14 3 0 57 71 5056K 4032K 0B 0B 100M 2485M 4950 151 sleeping 501 3633 234 1072 397 4902 com.apple.We 0.0 00:02.25 12 0 232 570 60M 48M 1116K 0B 427M 3853M 4902 1 sleeping 501 28093 1261 20314 8848
ps: display process status.
Most often used with '-f' (f for full) which shows more info
-a show info about all users
-x show processes without terminals
Example:
Lauras-MacBook-Pro:viewshedLI-paper ltoma$ ps
PID TTY TIME CMD
4631 ttys000 0:00.08 -bash
Lauras-MacBook-Pro:viewshedLI-paper ltoma$ ps -f
UID PID PPID C STIME TTY TIME CMD
501 4631 4629 0 10:45PM ttys000 0:00.12 -bash
Lauras-MacBook-Pro:viewshedLI-paper ltoma$
Lauras-MacBook-Pro:viewshedLI-paper ltoma$ ps -a
PID TTY TIME CMD
4629 ttys000 0:00.17 login -pf ltoma
4631 ttys000 0:00.08 -bash
4987 ttys000 0:00.00 ps -a
Lauras-MacBook-Pro:viewshedLI-paper ltoma$ ps -ax
PID TTY TIME CMD
1 ?? 1:47.34 /sbin/launchd
11 ?? 0:11.33 /usr/libexec/UserEventAgent (System)
12 ?? 0:06.76 /usr/libexec/kextd
13 ?? 0:05.50 /usr/libexec/taskgated -s
14 ?? 0:14.46 /usr/sbin/notifyd
15 ?? 0:14.78 /usr/sbin/securityd -i
16 ?? 0:01.55 /usr/libexec/diskarbitrationd
17 ?? 0:22.61 /System/Library/CoreServices/powerd.bundle/powerd
18 ?? 1:09.53 /usr/libexec/configd
...
Lauras-MacBook-Pro:viewshedLI-paper ltoma$ ls paper.* paper.aux paper.blg paper.pdf paper.tex paper.bbl paper.log paper.synctex.gz Lauras-MacBook-Pro:viewshedLI-paper ltoma$ ls paper.*>foo Lauras-MacBook-Pro:viewshedLI-paper ltoma$ cat foo paper.aux paper.bbl paper.blg paper.log paper.pdf paper.synctex.gz paper.tex Lauras-MacBook-Pro:viewshedLI-paper ltoma$
Lauras-MacBook-Pro:viewshedLI-paper ltoma$ ls _region_.prv layers-grid.graffle model-grid.graffle paper.bbl paper.tex _region_.tex layers-grid.pdf model-grid.pdf paper.blg plots acm_proc_article-sp.cls layers-layers.graffle model-layers.graffle paper.log region.pdf figures layers-layers.pdf model-layers.pdf paper.pdf sig-alternate.cls foo los.pdf paper.aux paper.synctex.gz vis.bib Lauras-MacBook-Pro:viewshedLI-paper ltoma$ ls -l |grep paper -rw-rw-rw-@ 1 ltoma staff 7276 Jul 2 2013 paper.aux -rw-rw-rw-@ 1 ltoma staff 2771 Jul 1 2013 paper.bbl -rw-rw-rw-@ 1 ltoma staff 883 Jul 1 2013 paper.blg -rw-rw-rw-@ 1 ltoma staff 22084 Jul 2 2013 paper.log -rw-rw-rw-@ 1 ltoma staff 2401983 Jul 2 2013 paper.pdf -rw-rw-rw- 1 ltoma staff 235898 Jul 2 2013 paper.synctex.gz -rw-rw-rw-@ 1 ltoma staff 86334 Jul 2 2013 paper.tex Lauras-MacBook-Pro:viewshedLI-paper ltoma$Another example:
Lauras-MacBook-Pro:viewshedLI-paper ltoma$ grep viewshed paper.tex|wc -l 95 Lauras-MacBook-Pro:viewshedLI-paper ltoma$This searches for all occurences of 'viewshed' in paper.tex, and displays each line where it matches. Then pipes this through 'wc' and counts the lines. There are 95 lines that contain occurences of the word 'viewshed' in paper.tex.