Shell Commands

List of Common Commands

( in alphabetical order )

cat

cat to look, modify or combine a file

 cat runs/mo-example/A.log | tail -n +10 | head -n 20-10+1 > B.log

cd

cd to change your current directory Go to your home directory

 cd ~

Go to a specified directory, e.g.

 cd /tmp

You can use

 cd -

to toggle between two directories with no effort at all.

cmp

cmp performs byte-by-byte comparison between two files.

diff

diff -b can be used to compare two files when the tabbing and whitespace has been changed in a code (tabbing, blank lines, spaces, etc). Regular diff will state that 'a=b' is different than 'a = b'.

dos2unix

dos2unix can be used to remove the ^M characters at the end of lines of your text files. However, if ^M appears not at the end of lines, this command will not remove it. You can use grep [ctrl-v][ctrl-m] yourfile to see whether yourfile still contains this character. You can then use vi yourfile and type command /[ctrl-v][ctrl-m] to search this character and then delete it.

find

find to search for files in a directory hierarchy

 find ./ -name param.inc

fmt

fmt makes multi-line text outputs fit nicely in a page by inserting and removing new lines.

grep

grep to show lines matching a pattern from files

 grep EPOT runs/mo-example/A.log
 grep -3 Stress runs/mo-example/A.log
 grep -w mea Fortran/MEAM-Baskes/meam/*

head

head to show the first several lines of the file

 head -n 20 runs/mo-example/A.log  #view the first 20 lines
 head -n -20 runs/mo-example/A.log #ignore the last 20 lines

nm

nm to list symbols from object files

 nm Fortran/MEAM-Baskes/meam/linux/forces.o | grep phiid

sed

sed to read the input file line by line

 sed  -n -e 10p -e 20p runs/mo-example/A.log #view the 10th and the 20th lines
 sed  -n 10, 20p runs/mo-example/A.log #view the lines from 10th to 20th   

sum

sum performs checksum of file. If the checksum is unchanged, the content of the file is likely unchanged.

tail

tail to show the last several lines of the file

 tail -n 10 runs/mo-example/A.log # view the last 10 lines of the file
 tail -n +10 runs/mo-example/A.log #ignore the first 10-1 lines of the file
 tail -f runs/mo-example/A.log # view growing log file in real time
 tail -c10 runs/mo-example/A.log #view the last 10 bytes of the file

tar

tar the tar archiving utility

 tar -zxvf MD++.tar.gz
 tar -jxvf highlight-2.6.5.tar.bz2
 tar -cvzf foo.tar.gz foo
 tar -cvjf foo.tar.bz2 foo
 tar cvf MD++.tar MD++ --exclude MD++/runs --exclude MD++/scripts/work --exclude MD++/cookies --exclude ".svn"

$ tar --create --tape-length=2097152 --file=results-NACL2-1.tar results-NACL2
Prepare volume #2 for `results-NACL2-1.tar' and hit return: n results-NACL2-2.tar
Prepare volume #2 for `results-NACL2-2.tar' and hit return: 
Prepare volume #3 for `results-NACL2-2.tar' and hit return: n results-NACL2-3.tar
Prepare volume #3 for `results-NACL2-3.tar' and hit return: 
Prepare volume #4 for `results-NACL2-3.tar' and hit return: n results-NACL2-4.tar
Prepare volume #4 for `results-NACL2-4.tar' and hit return:

yum

yum (Yellowdog Updater Modified) update program

 yum search gcc
 yum list installed | grep python-numeric
 yum remove python-numeric.i386
 yum install python-numeric.i386
 yum check-update gcc.i386
 yum update gcc.i386
 yum info gcc.i386

Other Resources

List of Unix Programs