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unixtricksandtips [2014/10/26 01:52] (current)
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 +==== Unit Tricks and Tips ====
 +alias l='ls -AFC'
  
 +-A all files except . and ..
 +-F add * to the end of executables,​ / to dirs, and @ to symlinks
 +-C multi-column output
 +
 +By the way, if you are an old time Unix geek annoyed by how
 +ls now does a case-insensitive sort on filenames who wants the
 +old behaviour back, add
 +
 +export LANG=C
 +
 +to your .bashrc.
 +
 +alias ll='ls -la'
 +
 +alias lll='​ls -laL'
 +
 +-l long format listing
 +-a all files (including . and ..)
 +-L follow symlinks, and list on the underlying file instead of the link
 +
 +alias lr='ls -ltra'
 +
 +-t sort by last modified time on files
 +-r reverse the sort order, so that newest come last
 +
 +ls -li
 +
 +-i list inodes
 +
 +
 +less -MQseai
 +
 +-M like more, only more so
 +-Q quiet (no terminal bells, ever)
 +-s squeeze multiple blank lines into one
 +-a start next search on next page
 +-i ignore case in searches
 +
 +g go to line 1
 +G go to end of file
 +N next file
 +P prev file
 +^L redraw the screen (general Unix idiom)
 +m[a-z] mark the file
 +'[a-z] return to mark
 +F follow
 +
 +export LESS=MQseai
 +
 +LESSOPEN
 +
 +
 +alias man='​man -a'
 +
 +-a display ALL matching man pages
 +
 +apropos (or man -k)
 +
 +man pages whose summary matches the input
 +
 +
 +find
 +
 +-name \*.html finds files that end in .html
 +-iname \*.html as -name, but ignore case
 +-follow follow symlinks
 +-xdev don't cross filesystem boundaries
 +-empty zero-length files and empty directories
 +-newer filename ​ find entries that are newer than filename
 +-perm mode, -mode, +mode  file permissions are exactly, all, or any of the bits in mode
 +
 +Learn to think about file permissions in octal.
 +
 +-type <​char>​ only look at <​d>​irectories,​ <​f>​iles,​ <​l>​inks,​ and so on
 +-print print matching names
 +-print0 print matching names delimited by \0
 +
 +Read the man page for find. Play with it. It will pay off.
 +
 +xargs <cmd> <​cmd-args>​
 +
 +Take lines from stdin, and comvert them into command args for cmd.
 +
 +-0 use \0 as input separator, instead of \n
 +
 +find and xargs are made for each other.
 +
 +cpio -pdumv
 +
 +copy entire directory trees, preserving everything
 +
 +find and cpio are also made for each other
 +
 +revmv, revln, revcp -- shell scripts to use with find and xargs
 +
 +
 +symlinks versus hard links
 +
 +symlinks
 +pros -- can cross filesystems
 +cons -- can have the rug pulled out from under them
 +
 +hard links
 +pros -- can't have the rug pulled out from under them
 +cons == can't cross filesystems
 +
 +
 +df, df -i
 +
 +display free space, or free inodes
 +
 +-h human readable
 +-k kilobytes
 +-m megabytes
 +
 +
 +du
 +
 +display usage
 +
 +-s summarise
 +-c total
 +-x don't cross filesystems
 +-h human readable
 +-k kilobytes
 +-m megabytes
 +
 +
 +sort
 +
 +sort files
 +
 +-b skip leading blanks
 +-n sort numerically
 +-k<n> sort on field n
 +-r reverse the sort order
 +-u uniq lines only
 +
 +Prefer to sort things so that the interesting bits come at the end.
 +
 +
 +uniq
 +
 +get unique entries in a file
 +
 +-c count occurrences
 +-d duplicated lines only
 +-u unique lines only
 +
 +cut
 +
 +cut the lines of a file into fields
 +
 +-c<​n>​{-<​n>​} columns
 +-f<​n>​{-<​n>​} fields
 +-d<c> delimiter
 +
 +paste
 +
 +paste lines from several input files together
 +
 +agrep
 +
 +grep files with multi-line records
 +
 +-d<​delim>​ record delimiter
 +
 +lsof
 +
 +list open files and network connections (run as root)
 +
 +-c<​command>​ list only <​command>​
 +
 +ifconfig
 +
 +show the network config for a box
 +
 +netstat
 +
 +show the network status
 +
 +-r show the routing table
 +-g show multicast group membership
 +
 +iostat
 +vmstat
 +sar
 +
 +Show the disk i/o, vm activity, and system activity report
 +
 +Specify a delay interval and a repeat count if desired
 +
 +pstree
 +
 +print process table as a tree
 +
 +basename
 +
 +get the basename of a file 
 +
 +dirname
 +
 +get the directory name of a file
 +
 +touch && >
 +
 +set the last modified time to now. touch will also create
 +the file if it does not exist. > will zero a file, or create
 +it if it does not exist.
 +
 +xxd
 +
 +hex dump a file
 +
 +objdump
 +
 +dump an object file
 +
 +-x dump all sections
 +--demangle turn C++ mangled names back to human readable names
 +
 +ldd
 +
 +list dynamic object dependencies
 +
 +namei
 +realpath
 +
 +find the real file
 +
 +time
 +
 +time a command
 +
 +tee
 +
 +split the pipe. send stdin to both stdout, and to a file.
 +
 +-a append to a file
 +
 +yes
 +
 +repeatedly output the same string
 +
 +column
 +
 +print stdin in multicolumn format
 +
 +tput clear
 +
 +clear the screen
 +
 +diff3
 +
 +diff three files (e.g. diff3 mine original yours)
 +
 +tr <​string1>​ <​string2>​
 +
 +translate characters in string1 to characters in string2
 +
 +-s squeeze multiple occurrences together
 +-c complement the first string
 +-d delete characters in string1
 +
 +sum && md5sum
 +
 +compute a simple checksum, or an md5checksum
 +
 +cal
 +
 +print a calendar
 +
 +dc && bc
 +
 +two quick and simple calculators
 +
 +tail && head
 +
 +print the last/first -N lines of a file
 +
 +tail -f follows a file waiting for new data
 +
 +seq
 +
 +output a sequence of numbers
 +
 +hostname, uname, /​etc/​redhat-release
 +
 +what is the hostname of the box, the unix name, and the redhat release
 +
 +nice && renice
 +
 +run a command at a lower priority, or change a running command'​s priority
 +
 +file
 +
 +identify what kind of file this is
 +
 +uptime
 +
 +how long has the system been up, and what is the load average
 +
 +screen
 +
 +start or reconnect to virtual screens
 +
 +kill && killall
 +
 +send a signal to running processes
 +
 +-HUP send a hangup
 +-KILL send a KILL (-9) to a process
 +
 +stat
 +
 +print stats on an inode
 +
 +strace
 +
 +trace all system calls from a running process
 +
 +comm
 +
 +compare two files, and produce three columns: uniq to file1,
 +uniq to file2, and comm-on to both
 +
 +ipcs
 +
 +interprocess communication statistics
 +
 +-l show limits
 +
 +<​code>​
 +/proc
 +
 +/​proc/​cpuinfo
 +/​proc/​meminfo
 +/proc/swaps
 +/​proc/<​pid>​
 +</​code>​
unixtricksandtips.txt ยท Last modified: 2014/10/26 01:52 (external edit)
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