# info > proc

---
type: CommandReference
command: proc
mode: man
section: 5
source: man-pages
---

## Quick Reference

- `cat /proc/[pid]/cmdline` — view command line of a process
- `cat /proc/[pid]/status` — view process status (state, memory, credentials)
- `cat /proc/[pid]/maps` — view memory mappings of a process
- `ls -l /proc/[pid]/fd/` — list open file descriptors of a process
- `cat /proc/[pid]/environ | tr '\000' '\n'` — view environment variables
- `readlink /proc/[pid]/exe` — get path of the executable
- `cat /proc/meminfo` — view system memory information
- `cat /proc/cpuinfo` — view CPU information

## Name

process information pseudo-filesystem

## Synopsis

shell
mount -t proc proc /proc
## Options (mount options)

- `hidepid=n` (since Linux 3.3) — controls access to `/proc/[pid]` directories
  - `0` — everyone may access all (default)
  - `1` — users may not access files inside other processes' `/proc/[pid]` directories (their own remain visible)
  - `2` — as for mode 1, but other processes' `/proc/[pid]` directories become invisible
- `gid=gid` (since Linux 3.3) — group whose members are exempt from `hidepid` restrictions

## Examples

**View the command line of process 1:**

shell
cat /proc/1/cmdline
**View the environment of process 1, with null bytes replaced by newlines:**

shell
cat /proc/1/environ | tr '\000' '\n'
**Find the current working directory of process 20:**

shell
cd /proc/20/cwd; pwd -P
**Use /proc/self/fd to redirect stdin/stdout:**

shell
foobar -i /proc/self/fd/0 -o /proc/self/fd/1
**View I/O statistics of a process:**

shell
cat /proc/3828/io
**Increase the system-wide file-max limit:**

shell
echo 100000 > /proc/sys/fs/file-max
**Drop caches (pagecache, dentries, inodes):**

shell
echo 3 > /proc/sys/vm/drop_caches
**View detailed memory consumption per mapping:**

shell
cat /proc/self/smaps
## See Also

[cat(1)](http://localhost/phpMan.php/man/cat/1/markdown), [dmesg(1)](http://localhost/phpMan.php/man/dmesg/1/markdown), [find(1)](http://localhost/phpMan.php/man/find/1/markdown), [free(1)](http://localhost/phpMan.php/man/free/1/markdown), [htop(1)](http://localhost/phpMan.php/man/htop/1/markdown), [init(1)](http://localhost/phpMan.php/man/init/1/markdown), [ps(1)](http://localhost/phpMan.php/man/ps/1/markdown), [pstree(1)](http://localhost/phpMan.php/man/pstree/1/markdown), [tr(1)](http://localhost/phpMan.php/man/tr/1/markdown), [uptime(1)](http://localhost/phpMan.php/man/uptime/1/markdown), [chroot(2)](http://localhost/phpMan.php/man/chroot/2/markdown), [mmap(2)](http://localhost/phpMan.php/man/mmap/2/markdown), [readlink(2)](http://localhost/phpMan.php/man/readlink/2/markdown), [syslog(2)](http://localhost/phpMan.php/man/syslog/2/markdown), [slabinfo(5)](http://localhost/phpMan.php/man/slabinfo/5/markdown), [sysfs(5)](http://localhost/phpMan.php/man/sysfs/5/markdown), [hier(7)](http://localhost/phpMan.php/man/hier/7/markdown), [namespaces(7)](http://localhost/phpMan.php/man/namespaces/7/markdown), [time(7)](http://localhost/phpMan.php/man/time/7/markdown), [arp(8)](http://localhost/phpMan.php/man/arp/8/markdown), [hdparm(8)](http://localhost/phpMan.php/man/hdparm/8/markdown), [ifconfig(8)](http://localhost/phpMan.php/man/ifconfig/8/markdown), [lsmod(8)](http://localhost/phpMan.php/man/lsmod/8/markdown), [lspci(8)](http://localhost/phpMan.php/man/lspci/8/markdown), [mount(8)](http://localhost/phpMan.php/man/mount/8/markdown), [netstat(8)](http://localhost/phpMan.php/man/netstat/8/markdown), [procinfo(8)](http://localhost/phpMan.php/man/procinfo/8/markdown), [route(8)](http://localhost/phpMan.php/man/route/8/markdown), [sysctl(8)](http://localhost/phpMan.php/man/sysctl/8/markdown)

## Exit Codes

Not applicable.